In the dive bar "Rote Katze," unemployed actor André is mistaken for a gang leader, whose charm attracts the interest of Gloria, the daughter of US jeweler Jefferson, who is said to have just acquired the famous "Halifax" diamond. The crook Pitou is also interested in the diamond and tries to ingratiate himself with the Jeffersons. When Pitou sees Gloria with the supposed gang leader André, he believes that André might also be after the "Halifax" and wants to confront him on the spot.