In 1970's Athens a group of professional burglars led by Azad (Jean-Paul Belmondo) plan a daring burglary. The victim is the rich gem merchant Mister Tasco (José Luis de Vilallonga). The treasure to be plundered is Mister Tasco's sumptuous emerald collection. The break-in team neutralize the villa's guard, enter the premises and locate the safe. Their sophisticated safe-cracking tools allow the burglars to break the safe open and steal the emeralds. During the caper a lone Greek policeman notices the burglars' car parked outside the Tasco residence and becomes suspicious. When Azad pretends to tinker with the getaway car's engine the Greek cop pretends he believes him. In fact, the Greek Police inspector Abel Zacharia (Omar Sharif) suspects a burglary is taking place but decides to play along in order to allow the burglars to complete their mission. However, the corrupt Greek cop intends to arrest the criminals later and to steal the emeralds for himself. A cat and mouse chase ensues.