Terry is the chief car tester for Emery Motors and Frank is an Engineer. Jane has just been hired to work in publicity. Frank and Terry both want Jane to be their girl. Terry has designed a new carburetor that should bring him fame and money, but he cannot get it to work correctly. Terry and Gadget have tested it for over a year, but it still is not perfected. Emery Motors assigns Frank to help Terry with the carburetor, but Terry is not happy because Frank is an Engineer and is also vying for Jane. They finish the carburetor, and to test it, they enter a car in the Indianapolis 500 race. Terry is not yet satisfied with the carburetor before the big race even though it has passed all the tests.

Jeff Elliot is an American GI investigating a black market gang in Munich.

In Chicago, an unemployed actor aims to solve the mystery concerning a string of ax murders, apparently committed by a lunatic.

Angered that her sister Celia has stolen her fiance, Dell Faring kills her and allows Celia's husband David, knocked out in an argument with Celia, to take the blame and end up on death row. Later Dell, finding out that David's young daughter Susan was witness to the crime and is undergoing psychiatric treatment, plans to eliminate her before her memory returns.