When he is arrested and sentenced to be executed for murdering a young medical student who volunteered to be killed to test the procedure, Savaard vows retribution on the individuals responsible.

The Man They Could Not Hang is the first in a series of four similarly-themed but otherwise unrelated horror films produced by Columbia Pictures, all starring Karloff, informally known as the "Mad Doctor Cycle."

Bob Roberts, a young medical student, volunteers himself to be temporarily killed in order to test an artificial heart developed by Savaard.

Bob's fiancée, Ms. Crawford, fears that the experiment will fail, and rushes to a police department to alert law enforcement.

Over the month following Savaard's execution, six of the jurors from his trial are found hanged in apparent suicides, a commonality noticed by reporter 'Scoop' Foley.

Janet heads downstairs and, in spite of her father's pleas, purposefully touches the electrified grille, forcing Savaard to surrender.

[7] In 2006, the film was included on a four-film DVD release titled "Icons of Horror Collection: Boris Karloff", accompanying The Black Room (1935), Before I Hang (1940), and The Boogie Man Will Get You (1942).

[8] In 2021, The Man They Could Not Hang was released on Blu-ray in Region B by Eureka Entertainment, as part of a six-film box set known as "Karloff at Columbia".