An assertiveness course gets a shy guy mixed up with racketeers at an amusement park.

Spineless Eddie Pink, who runs a handy man shop at Millwood University, is continually bothered by bullies. His only protector is the kindly but dense Butch Carson, who has been a senior for three years. Eddie subscribes to a mail order character building course, which promises to turn him from a mouse into a man by giving him a forceful personality. Meanwhile, Butch confides in Eddie that he must graduate this year in order to help his mother Hattie and her secretary, Claribel Higg, who run the Dreamland amusement park. They are beleagured by racketeer Vance and his gang, who are trying to force them to install crooked slot machines in the park. Eddie helps Butch pass his final exam, and Hattie is so grateful that she makes Eddie co-manager of Dreamland with Butch. After graduation, Eddie and Butch go to the Club Lido, which features torch singer Joyce Lennox. Eddie has adored Joyce from afar for years, and he does not know that she is Vance's girl friend. The next day, Eddie is at Dreamland when he is approached by Vance's henchmen, Copple, Marsh, Selby and Thrust, about installing the slot machines. With Claribel's help, Eddie gets rid of the mugs, but their jubilation is quickly soured when they discover that Butch, who has joined the Navy on a whim, will be leaving immediately. Eddie is dismayed about being left in charge of Dreamland, especially when Copple returns with a hired gun named Killer. Eddie tries to use his forceful personality on Killer, but finds that Killer has taken the same correspondence course. Fortunately for Eddie, Killer has not finished the book, and Eddie is able to outwit him. Later, Hattie and Claribel talk Eddie into hiring a bodyguard, Nick Parkyakarkus. After a week has passed, Claribel realizes that she is in love with Eddie, while Vance gets tired of his men's failures. Vance decides to use Joyce to trap Eddie into cooperating, and he arranges for Eddie to witness what appears to be Joyce murdering her brother Chorley. Desperate to protect his dream girl, Eddie tells Vance that he killed Chorley when the gang pretends to question her. Vance tells Eddie that he will hush up the affair if Eddie puts 150 slot machines in Dreamland. When Eddie protests that the machines are crooked, Vance has him test one that pays him a jackpot. Believing that all the machines will pay out, Eddie agrees, and the machines are delivered the next day. Hattie and Claribel are horrifed, and after Claribel realizes that Eddie allowed them in to protect Joyce, she orders him to leave. Eddie, who has discovered that the machines are rigged, goes to Joyce's apartment, where he finds Chorley alive. Eddie then hides and records Vance and Chorley discussing their racket, but the crooks see him as he attempts to flee. Eddie returns to his office and shares his discoveries with Claribel, who summons the police. The gang arrives, and after they chase Eddie and Parkyakarkus through the park's rides and into a hot air balloon, they are finally apprehended by the police. An exhausted Eddie agrees to marry Claribel, and she uses his forceful personality tricks to entice a kiss from him.