Convicted bank robber Archie Kovis is released from a prison outside London, England. His girl friend, Sally, drives him home, unaware that they are being followed by Charlie Hodgson, a diamond merchant. Once Sally and Archie are home, Charlie dents their car and leaves a note on the windshield. The next day, Charlie gives Sally £200 to repair the car and hands her an invitation to a dinner party at his home. Among the guests at the party is Charlie’s younger brother, Earl, who designs security systems. Meanwhile, Archie breaks into Charlie’s study and attempts to open the safe. Armed with a pistol, Charlie catches Archie in the act and claims that a safe designed by Earl is impenetrable. After handcuffing Archie to the safe, Charlie brings Sally into the study and admits he has been observing the couple for five years. He offers $100,000 for their assistance in planning and executing the only crime he will ever commit: robbing the diamond exchange in Tel Aviv, Israel, which is equipped with a security system designed by Earl. Later, in Tel Aviv, police captain Moshe Ben-David is presented with a dossier on Archie, who is currently en route to Israel, accompanied by a woman. Moshe goes to the airport and intercepts the couple at customs, asking routine questions about their visit while Moshe's subordinate, Gaby, photographs them from a distance. Charlie passes through customs uninterrupted and is taken to a hotel by his driver, Mustafa. After arriving at their hotel, Sally and Archie discover that Gaby is staking them out, and they leave for Bethlehem early the next morning to meet Charlie. Before leaving Tel Aviv, Charlie is introduced to Schlomo, described by Mustafa as, “the most important man in the country” and very honest, despite his five prison terms. Charlie and Archie meet at the Church of the Nativity, where they plan to steal the gold crown from the Madonna statue and replace it with a copy. Later, Charlie makes a large purchase from merchant Avram Karan at the diamond exchange. Aaron acquaints Charlie with the building’s security systems, including the floor surrounding the vault, which triggers an alarm in the presence of intruders. Charlie rents a safety deposit box and is issued an identification card by chief custodian David Rabinowitz. Later, Schlomo follows Rabinowitz, who bicycles to a playground to pick up his young son, Danny. The following day, Moshe and Gaby break into the workshop where Archie is making his replica of the Madonna’s crown. The police confiscate a stack of photographs, several of which include Charlie. Shlomo kidnaps Danny and contacts the boy’s father, demanding the combination to the vault in exchange for Danny’s life. Rabinowitz reluctantly submits to the demand. That evening, Archie, Sally and Mustafa take the counterfeit crown to Bethlehem, with a group of detectives on their trail. In Tel Aviv, Charlie has a drink in the restaurant at the diamond exchange and awaits the departure of the daytime employees. As the building empties, Charlie climbs into a ceiling vent. In Bethlehem, a Christmas celebration is underway as Archie and Sally enter the Church of the Nativity. They disguise themselves as a priest and an elderly woman, and leave the church undetected by the policemen stationed outside. Moshe and Gaby arrest Mustafa and question him about his connection with Charlie. Sally and Archie doff their disguises and drive to a waiting helicopter, which flies Archie to the roof of the diamond exchange. With the help of a portable computer, Charlie and Archie manipulate the elevators to take them in between floors, where they gain access to the vault via the ventilation system, enabling them to avoid security cameras. After Charlie breaches the final barrier with his identification card, Archie makes his way to the vault using a pair of stirrups that attach to the ceiling. Meanwhile, Moshe telephones Arik, the chief security guard, to ask if he is aware of any unusual activity. Despite Arik’s assurance that there are no intruders, Moshe and Gaby head for the exchange. Rabinowitz, overwhelmed by guilt over his betrayal, bicycles to the exchange in hopes of thwarting the robbery. Archie unlocks the vault and finds millions of dollars worth of diamonds. However, Charlie instructs Archie not to remove any of the stones, revealing that the operation was only intended to expose weaknesses in his brother’s design. Archie defies Charlie and gathers all the diamonds he can carry. He ignores Charlie’s threat to lock him in the vault until a handful of diamonds fall onto the floor, triggering the alarm. Moshe, Gaby and Rabinowitz, along with several security guards, head to the vault. Charlie and Archie narrowly escape their pursuers and radio Sally to send the helicopter for them. As the disheartened detectives leave the exchange, they see Charlie and Archie smiling at them from the crowd that has gathered outside. Inside the building, Rabinowitz is informed that his son has been returned safely. Later, Moshe and Gaby escort the three conspirators to the airport. The police captain thanks Charlie for the important lesson, but asks that he perpetrate his next such undertaking in a different country. Charlie gives the detective an envelope and asks him to keep it sealed until the plane departs. Before boarding their plane, Charlie hands Archie and Sally $100,000 in cash. Archie responds by punching Charlie in the jaw, to which Charlie replies, “Fair enough.” As the plane takes off, Moshe opens the envelope, which contains a key to Charlie’s safety deposit box. Charlie requests that the contents, approximately $100,000 in cut diamonds, be split evenly between the Rabinowitz family, to pay for Danny’s education, and the diamond exchange, to improve its security system. At that moment, the detectives see Charlie’s brother, Earl, coming toward them. On the plane, the three conspirators drink a toast to their achievement.