Jilted by her ex-boyfriend Jeff Logan, Shayne (the leader of an all-female motorcycle gang) and her new boyfriend Lon decide to torment Jeff and his new bride, Connie. The harassment backfires when Shayne's sister Edie is accidentally killed by a Molotov cocktail and when Shayne herself ends up hanging by her fingernails off a cliff.
Maury Dexter says the film was the most successful of all the ones he made at AIP.[2]
From Nostalgia Central:
There is plenty of rambunctious vitality and crude humour but the film never stoops for the cheap thrill. It’s sharply-paced, well-photographed, and the whole production has a great sense of freedom.[3]