Nick Dunn, a used car salesman, can't close a deal with customers Karen Winter and Arthur Markel, so he is fired. A sympathetic Markel has a car lot of his own and offers a job to Nick, who quits after discovering Markel's disreputable sales methods.
Nick and wife Jane have a financial dilemma when their son falls ill. Swallowing his pride, Nick asks for his job back with Markel, who promotes him to manager. But the criminal activity continues, until Nick becomes convinced that Markel has even ordered his henchman, Smiley Ward, to murder Davenport, a detective.
Jane is appalled by Nick's new line of work. He seeks solace in the company of the beautiful Karen, but when the cops come to investigate Davenport's death, Karen refuses to give Nick an alibi. Now a suspect, he tracks down Ward, who during their struggle at an amusement park falls from a roller coaster to his death. Nick tries to explain the hot-car racket to the police, implicating Karen and Markel.
