Officers Jim Street and Robert Duran of the WCPD's Olympic Precinct, dispatched to a fake emergency call, are ambushed by a trio of cop killers; the newly-established Olympic SWAT team arrives, led by Lt. Dan "Hondo" Harrelson, but the gunmen escape, leaving Duran dead and Street devastated. The shooting is just one more casualty in a series of ambushes by the trio to avenge the death of gunman Dallas's uncle, allegedly in police custody. Street opts to attend SWAT training in the hopes of avenging Duran, and Hondo selects Street for the team alongside natural marksman Travis Joseph "T.J." McCabe. The attacks continue as the gang prepares one final ambush before fleeing the city, but SWAT catches on and moves to disrupt them; in the ensuing operation, two of the gunmen are apprehended and Street kills the last, but he realizes revenge is meaningless and can never satisfy him. As the gunmen are booked, Hondo reveals their revenge was based on a misunderstanding—Dallas's uncle had killed himself to avoid arrest—and muses on the pointlessness of killing before returning to duty with his team.

Joey Hopper is broken out of a hospital prison ward by the Hopper family, a violent Satanic cult led by Joey composed of disaffected youths, responsible for a string of brutal murders and narcotics crimes. As Olympic SWAT joins the citywide manhunt for the Hopper family, Hondo finds himself targeted by Joey for having apprehended him earlier, while an underground newspaper editor at odds with the WCPD turns to Hondo for help when his daughter is drawn into the Hopper family. Tracking them down to a remote farmhouse, SWAT besieges the Hopper family and uses tear gas to smoke them out, while Joey is killed when he takes the editor's daughter as a human shield. With the threat subsided, Hondo celebrates his anniversary with his wife Betty, initially interrupted by the manhunt.

Frank Thomas is shot and killed by a sniper on the freeway, the third in a string of calculated yet seemingly random sniper attacks. As Olympic SWAT investigates, they learn two of the men dated the same woman, fashion model Janet Warren. Hondo devises a plan to draw out the sniper: having a SWAT officer go undercover as her new boyfriend. Street is selected for the role, and gradually falls in love with Janet, but becomes targeted by the sniper, Eric, a dressmaker working in Janet's company seeking to make her fall in love with him. When Eric kidnaps Janet, Street catches on and trails him to the coast, where SWAT battles him while Hondo scales a cliff to flank him, eventually reaching Eric and Janet in time to kill Eric before he can kill Janet in a murder–suicide. Though she is no longer under threat, Janet, shaken by the losses she endured, decides to leave the city, and visits Street and the team one last time to bid farewell.

With Olympic SWAT busy handling standoffs and monitoring an APB on a kidnapped high school girl, freelance writer Meredith Cooper is embedded with SWAT for a human interest article in a magazine. Cooper is infamous in the WCPD as a staunch police critic who views SWAT as "a necessary evil, but more evil than necessary", but they cooperate nonetheless. However, the day's difficulties worsen when Hondo, already struggling with SWAT calls interrupting his family life, is called to the hospital during a standoff after his son is struck by a car and injured. Later, SWAT is deployed for a plainclothes takedown when the kidnapped girl is spotted on a ferry, but when Cooper follows the team aboard and unintentionally provokes the kidnapper, the officers are forced to shoot. With the day finally over, Hondo finds time to get his family life together.

Infamous drug kingpin Vincent Ritchie agrees to testify against his former associates before a committee, but is critically injured and hospitalized after his police escort is ambushed. Olympic SWAT is assigned to the hospital to protect him, while Dominic Luca enters a relationship with his disaffected daughter—but the situation becomes tense when a police ploy uncovers a mole in the hospital staff, sent to confirm Ritchie's death. With Ritchie scheduled for one final surgery, his former associates deploy a team of hitmen to assassinate him by any means necessary, but SWAT manages to fight them off, only for Luca and Hondo to catch Ritchie's daughter trying to kill him on her own terms. Ritchie ultimately survives and reveals dozens of crime bosses to police and the public, while Luca accepts he is still single.

Bo Pritchard, Hondo's comrade from the Vietnam War and a known cowboy cop trying out for SWAT, joins Hondo and David "Deacon" Kay at the scene of a botched burglary. When Deacon is shot by the suspect and Bo shoots the suspect despite the team having him at gunpoint, Hondo chooses to hire Bo as a temporary replacement while Deacon is hospitalized. However, Bo's violent and uncooperative nature leads to tensions between him and the team, worsened when Bo covertly threatens Deacon with full replacement in SWAT. When Bo escalates another hostage-taking and forces T.J. to shoot the mentally-disturbed suspect, Hondo kicks Bo off the team. Bo suffers a mental breakdown and kidnaps Betty to draw Hondo out to fight him personally; Hondo obliges and, after a brief fistfight in a warehouse, manages to defeat Bo and rescue Betty. In the aftermath, Deacon fully recovers and is brought back to the team.

Olympic SWAT responds to a sniper targeting an ambassador, committed by the "Organization for the Freedom of Oppressed People", purportedly a Middle Eastern left-wing terrorist group active in California. Unbeknownst to the police, the Organization is actually a front for a criminal group, part of a complex plot to rob the Owls basketball team (one player of which, Ollie, is a longtime friend of T.J.'s) for $2 million, using the terrorist charade as a way to pressure the authorities into acquiescing to their demands. When the group launches their attack at the Sports Arena and takes the Owls hostage, Hondo's attempts to negotiate a release are stymied by political pressure and the wounding of a player, and he is forced to follow their demands. However, quick thinking from Ollie and strategic placement of the team leads to the entire group being apprehended and the Owls being freed.

Olympic SWAT is assigned to protect a U.S. Senator, known for his strong anti-gambling stance, and rescues him from an attack by frogmen. With the attempted assassination a failure, a gambling magnate hires a professional hitman from overseas, who steals an ArmaLite AR-18 from a National Guard armory and prepares an ambush while enjoying himself in the United States. However, when several people the hitman comes into contact with—including the gambling magnate, a National Guardsman, a young boy, a waiter, and his date—fall ill with a severe form of pneumonic plague last reported in India, SWAT is pressured to find the increasingly-ill hitman before he potentially sparks a deadly epidemic. The hitman's attempt on the Senator's life fails, and SWAT pursues him to a water reservoir, but he falls in and dies before he can be apprehended.

An empty armored car is stolen from a security company overnight. Though no valuables were stolen, Olympic SWAT is alerted, as the armored car is practically impenetrable and could be used for anything from robberies to terrorist attacks. As SWAT follows up on the armored car theft, T.J. brings Luca to the American Beauty Contest, where his fiancée Susan works as a photographer; unbeknownst to them, the contest is the target of the armored car's thieves, a gang of veterans seeking to steal the bejeweled crown and scepter worn by the winning girl, worth over $2 million. The gang disguises themselves as the armored car crew scheduled to retrieve the crown and scepter, but takes Susan and the winning girl, Miss New Mexico, hostage in the armored car when they learn the crown and scepter used in the event is a fake copy, stealing the real one from the event organizers. SWAT surrounds the van and, after an intense standoff, manages to use paint shells and a flare launcher modified to fire gas to smoke out the fake guards and rescue Susan and Miss New Mexico.

At Street's university, students prepare to protest the Biological Weapons Convention, which they believe was not followed by the U.S. military, and an alleged experimental biological warfare program by Omega Chemicals involving Dr. Brunner, Street's professor. However, a group of radicals led by Stockwell use the protest as a cover to take over the Omega One chemical plant and demand a $1 million ransom lest the plant explodes, taking Brunner and his wife hostage. Olympic SWAT, following up on a gun shop robbery related to the radical plot, is alerted to the attack. With the radicals setting a deadline of just three hours, Hondo delivers the ransom while the rest of the team infiltrates the plant to apprehend the gunmen. After Stockwell takes Hondo as a human shield and T.J. shoots him, Brunner remembers the plant's override code—the date of the attack on Pearl Harbor, Franklin D. Roosevelt's "day of infamy"—preventing the explosion and saving the city.

During a standoff at a massage parlor, Hondo is grazed in his head. Though he survives and refuses medical attention, the injury begins to take its toll: his vision blurs, he becomes disoriented and aggravated more often, and he nearly faints at a standoff. Finally accepting the injury affected him more than he thought, Hondo learns he has a concussion and decides to retire from frontline duty, handing command of Olympic SWAT to Lt. Purcell, a rough commander from Riverside Precinct who is often at odds with the team. However, Hondo decides he is dissatisfied with desk work and opts to undergo a risky surgery to undo the damage. The operation is a success and Hondo returns to commanding Olympic SWAT, successfully resolving a hostage situation through negotiation alone.

Olympic SWAT shoots and arrests a gunman in an amusement park, devastating his young son, who may be without parents as his mother is hospitalized following a heart attack. When the boy runs away from his youth shelter, Hondo finds him checking on his mother, and offers to let him stay in the Harrelson household for the time being. Meanwhile, a former parole officer scopes out SWAT's response in preparation for a heist at a coin collection auction; his crew plans to use a series of random shootings and explosions as a diversion. The heist is pulled off, and the diversion is launched; the police are initially fooled, but SWAT catches on when a silent alarm at the auction breaks from the pattern. The team deploys to the auction and apprehends the heist crew, while the boy's mother eventually recovers and takes custody of him.

A crew of thieves pull off a string of violent robberies with the same modus operandi: they hold up a jewelry store, take a woman hostage, and use her to intimidate the responding officers and get away before they can pursue. In reality, the woman is part of the crew, who are planning to offload their loot and get away using diving equipment at the docks, using a dive center as a front. Olympic SWAT is as confused as the rest of the police department, but the suspicious murder of a fisherman known to Hondo by one of the thieves leads them to connect the dots.

A training exercise with another division's SWAT team is interrupted by the murder Officer Frank Baylor (Don Eitner), found with the words "Kill S.W.A.T." pinned to his chest. Olympic SWAT soon learns the murder is just the first in a series of attacks targeting SWAT officers by two brothers and their fanatic sister-in-law, who seek to avenge her husband's death in the first ever SWAT deployment.

Olympic SWAT is called in to handle crimes committed by suspects carrying powerful automatic weapons. Luca and T.J. are sent on an undercover assignment to discover the source of the weapons.

After training with a (then-new) beeper at a movie studio, Street picks up his girlfriend, but remembers he forgot his beeper and returns to the studio to retrieve it. While there, Street and his girlfriend find themselves in the middle of a bombing plot by a disgruntled stuntman and his team to extort the studio and destroy the film sets—but with the security guard murdered, the entire studio occupied, and his equipment back at the station, Street and his girlfriend fight to survive and call for help before the bombs can go off.

The Brewer brothers are arrested by Olympic SWAT for trying to prevent the demolition of their home by construction magnate Carl Rigby. Meanwhile, Mel Lang (Paul Mantee) and Ralph Costa (Aldo Ray), a pair of ex-convicts who were reported by Rigby and arrested by Hondo, seek to exact their revenge against them, and kidnap the Brewer brothers, seeking to frame them for the planned murders.

Two teenagers seeking shelter in the warehouse of Colby Electronics anonymously alert Olympic SWAT after a group of criminals break in and kill two police officers. Before they can escape, a teenager sees the face of one of the criminals—former U.S. Senator Greg Colby(Carl Betz). Learning he has been seen, Colby befriends Hondo to follow up on the investigation, in the hopes the police will identify the witness and allow him to assassinate them.

Paul Julian (Harris Yulin) uses a radio scanner to listen to police radio frequencies in the back of his repair shop. Though on the surface he presents this as a hobby, in reality he uses it to operate as a vigilante sniper and kill suspects, even those who have surrendered, as a way to avenge his murdered wife. After Julian intervenes in two standoffs that would have been resolved peacefully, Olympic SWAT, facing intense media pressure and accusations of being behind the shootings, seeks to stop Julian before another killing—without knowing he is actually their own radio repairman.

Olympic SWAT intervenes in a daring heist at the race track and apprehends Howard Wilson (Bill Fletcher), one of the robbers. His escaped accomplices, aided by unscrupulous attorney Jason Bridges (H. M. Wynant), work to get the charges dropped and make Wilson a free man—by force.

Olympic SWAT is assigned to help transport convicted dope dealer Johnny Rizi (Frank Gorshin) to prison, but his former associates seek to silence him before he can testify against them. After escaping a sniper attack at the heliport, Hondo joins Rizi in a police helicopter flight to the jail and cuffs himself to him, but learns too late that the helicopter has been sabotaged by the hitmen. When the helicopter crashes in a remote valley, an injured Hondo is only able to radio in his rough location, drawing the team—and the hitmen—to search the area for Hondo and Rizi, who must learn to trust each other to survive in the wilderness.

General James Woodward (John Dehner), a war hero turned neo-Nazi militia leader, prepares to launch his political campaign, but faces staunch opposition from both the public and from within, as Woodward's aides plan to launch a putsch and assassinate him on live television. Olympic SWAT is reluctantly assigned to provide security, but tensions arise between the neo-Nazis and the team over Deacon's race. An attack by "black militants" (really neo-Nazis in blackface) draws heavy security to a televised rally and sets the assassination in place, but Olympic SWAT sees through the plan and defeats the assassins.

Prosecutor John Stevens (Ed Gilbert) holds secret information which could convict two syndicate chieftains of capital crimes. Because Stevens insists on saying nothing until the grand jury convenes, and because police believe the mob has put out a major contract on Stevens, Olympic SWAT is assigned to protect him. However, the syndicate's enforcer plans to abduct the Stevens' daughter Tory (Jane Alice Brandon) and keep the girl until the father turns over the evidence. Oblivious to the danger, Tory is out for kicks as both the police and the syndicate to track her down.

A group of men steal a tugboat and barge laden with twelve cases of TNT, killing the tugboat captain in the process. They later threaten to blow up a Nobel Prize-winning marine biologist and her research vessel unless they are given one million dollars.

Marco (Peter Breck), an arsonist posing as a firefighter, engineers a fire during Southern California's dry season in the area's most affluent neighborhood, Sherwood Heights. While looting the evacuated home of a wealthy couple, one of Marco's men shoots a fireman. When Olympic SWAT is called in to locate the sniper, McCabe (James Coleman) is shot and gravely wounded. The team kills one of the snipers, but Marco and the rest of his gang escape with a truckload of stolen merchandise.

Hondo's old friend, millionaire Doris Wainwright Bristol (Anne Francis), has brought expensive jewelry into the hospital where she is undergoing cosmetic surgery. Her bodyguard, Joe DeLeon (Frank Campanella), is slain after he spots criminal Frank Malloy (Michael Callan) posing as a dying patient; all part of a plot to steal Doris' jewelry. Olympic SWAT, who along with Hilda (Rose Marie) are at the hospital preparing for the children's Christmas party, find themselves forced into action when the discovery of DeLeon's body leaves Doris unprotected.

David Neal (Stuart Whitman), a government agent who spent four years on an undercover assignment posing as a crime boss's lieutenant, is marked for death after his testimony sends the kingpin to prison for life. After the trial, a $500,000 bounty is put on the head of Neal, who begins a new life in a small town as Ben Jordan. However, his police instincts come to the fore and he soon finds himself embroiled in another battle with organized crime.

Lt. Harrelson and his team are called to investigate two robberies in which powerful drills, cutting equipment and dynamite are stolen. During the investigation, Luca sets up a double date for himself and T.J. with Sharon Merlingdale (Monie Ellis), a witness from another case and a student at a prestigious all-girls school, and a classmate. The thieves, who are planning to use the school as an entry point to a bank vault across the street, were counting on the school being empty for the weekend. When the girls agree to stay the weekend for their dates, they unwittingly place themselves and Luca in grave danger.

Bud Haskins (Eric Boles), whose father John is moving large quantities of unmarked automatic weapons as part of his warehouse operation, agrees to help three men crack open the safe in the elder Haskins' warehouse. Bud has had a falling out with his father and wishes to steal some of the money in the safe. When the thieves attempt to steal some of the weapons, Bud is killed trying to stop them. While Olympic SWAT is assigned to investigate the burglary-murder as part of their ongoing effort to locate the source of the weapons, John Haskins (Mark Stevens) recruits his Eastern mob partners to find his son's killers.

Lt. Eddie Chew (James Shigeta) is assigned to aid Olympic SWAT when an elderly shop owner is beaten by an undocumented Chinese immigrant working as a shakedown man for Ronald Parker (played by Joel Fabiani); Parker is the Caucasian leader of what appears to be an all-Asian crime syndicate engaged in a protection ring. Hondo begins to doubt Chew's integrity when it becomes obvious that the Chinatown criminals are being given secrets of his investigation.

Olympic SWAT pursue a group of men who are terrorizing the entire area by committing a series of rapes. The only clues are a religious medal found at one of the abduction scenes and a Biblical quotation overheard by one of the victims.

A group of militants take over a radio station and demand their jailed leader be released or they will blow up the station, along with their three hostages.

A mentally unstable veteran who has escaped from a psychiatric hospital is touring a movie studio, when he suddenly thinks he is back fighting in Vietnam. He takes two people hostage, leaving Olympic SWAT with the task of disarming him.

After being severely wounded in an operation, Hondo fights for his life during a lengthy brain surgery. While waiting at the hospital, the four team members reminisce about their best moments with the Lieutenant (in clips from previous episodes).

Luca (Mark Shera) is charged with manslaughter after he is forced to kill a man who was holding his own wife hostage at gunpoint.