Scotland Yard is after a homicidal maniac called The Blue Hand, which is what he uses to kill his victims.

In this Swiss film noir a private investigator stumbles onto a case involving blackmail and an oversexed, under-aged girl. He finds the girl, and, tragically, becomes involved with her.

Filmed during the annual 24-hour endurance race at Le Mans, Michael Delaney is a Porsche driver haunted by the memory of an accident at the previous year's race in which a competing driver was killed. Delaney also finds himself increasingly infatuated with the man's widow.

Hugo Wiederkehr, as a dutiful bank employee, has to deal with all kinds of customers. Among other things, with the industrialist Meissen and his pretty daughter Christine, with whom he falls in love. However, it remains unmatched because it belongs to a different social class. He also works as a hobbyist and inventor, which also requires a lot of money. When his employer refuses to give him a loan because his father is in prison for fraud, he quits disappointed.