Recently paroled from prison for practicing medicine without a license and selling phony stock, John Muller (Paul Henreid) is given a boring menial job by the parole board, but seeks a big score and pulls together his old crew to knock over a local casino owned by Rocky Stansyck (Thomas Brown Henry). Overlooking a few details on the casino's security Muller barely gets away while some of his cronies are killed. While laying low with yet another menial job, Muller is mistaken for a psychologist Dr. Bartok who looks like Muller except for a large scar running down one cheek. When Muller snoops into the doctors business he meets his secretary and lover Evelyn Nash (Joan Bennett) and continuing to spend more time with her to get information, he falls in love with her. Muller studies books on psychology and also studies the doctor's patient files and stalks the doctor and takes a photo of him and, with surgical tools, scars his face just like the doctor but when he knocks off the doctor he realizes that he has scarred his own face on the wrong side. Muller continues with the charade but when his brother Frederick Muller (Eduard Franz) tracks him down Evelyn realizes the truth but decides to leave town with Muller. But Muller has overlooked some details of the good doctor's lifestyle and some involvement with gamblers that catch up to the man at an unexpected surprising moment.
What does Muller need in order to be able to completely portray the doctor?
Scar