Helmut Schmidt is an ambitious Interpol inspector. He follows a trail of dangerous drug dealers that leads to Hamburg. With the colleagues there, he decides to infiltrate the gang. The beautiful dancer Arlette helps him.
Two old sea dogs are fighting to the teeth for customers for a coastal cruise. Three crooks turn up at the resort and try to get a briefcase full of valuable jewelry out of the three-mile zone. A rich "Frenchwoman" is also involved in the affair. An insurance agent mingles with the tourists without being recognized in order to track down the jewel thieves.