Through a long interview with the subject and his wife, archive footage and some dramatic reenactments, the film tells the story of Manhattan Project physicist and Soviet Union spy Theodore Hall.
On the review aggregator website Rotten Tomatoes, 81% of 47 critics' reviews are positive, with an average rating of 7/10. The website's consensus reads: "A Compassionate Spy's personal approach to its real-life story makes the end result mostly compelling despite an uncritical tone that verges on hagiography."[9]Metacritic, which uses a weighted average, assigned the film a score of 72 out of 100, based on 20 critics, indicating "generally favorable" reviews.[10]
The reenactments were criticized by Guy Lodge from Variety, who described them as "unnecessary", making the film "more televisual than in James's best work".[11] David Ehrlich from IndieWire wrote that the reenactments were a "miscalculation that keeps [the film] at arm’s length."[12]