In 1950s Southern France, gun smuggler Pedro Wassewitch is running a crime ring from his villa. In the caves dug under his property, Pedro stores a vast arsenal of weapons and ammunition. In the post-war years, abandoned weapons of all calibers are readily available in France. The French police wants to put a stop to the arms trafficking. They organize a sting operation to capture Wassewitch and find his secret arms stash. Therefore, undercover police inspector Ludovic Ferrier is sent to contact Wassewitch and convince him that he represents a client who wishes to purchase a large consignment of illegal weapons. Although suspicious by nature, Wassewitch cannot resist the prospect of a large sale for a huge profit. Nevertheless, he insists on directly talking on the phone to Ludovic Ferrier's boss, a certain Mister Albatrasse, who is an arms smuggler himself and has a reputation among criminals. The French police has to figure out how to impersonate Mister Albatrasse during the phone calls with Wassewitch. Wassewitch is under police surveillance but the undercover cop Ludovic Ferrier is shadowed by Wassewitch's men too. During the cat-and-mouse game both Ferrier and Wassewitch pretend to trust each other. However, Wassewitch notices that his wife, Lola, is attracted to Ludovic Ferrier. Although very jealous, Wassewitch keeps his cool hoping to clinch the arms sale. When the night of the arms sale arrives, things get out of hand. The police must rush to capture the members of Wassewitch's gang and surround Wassewitch's property where he and his vast underground arsenal of weapons are located. However, the real Mister Albatrasse escapes from police custody and is hell bent on warning Wassewitch about the trap. The life of undercover cop Ludovic Ferrier is in grave danger.