The film opens with Salomon (Sali) gambling extravagantly and achieving victory at a Monte Carlo casino shortly after the war's conclusion. The narrative then takes us back to the late 1930s in Germany, where Sali is portrayed as a vibrant figure, engaging in parties, shady deals, and is recognized as a successful forger. At one of these gatherings, he encounters a woman who persuades him to forge an Argentinian passport for her, clearly intent on escaping Nazi Germany. He brings her to his home, where he skillfully crafts the fake passport, leading to an intimate night together.
However, their morning is abruptly interrupted when the police storm in, arresting Sali. The lead detective, Friedrich Herzog, takes pleasure in capturing "The King of Forgers." The story then jumps five years ahead, showing Sali's grim transition from prison to a concentration camp. He, along with other inmates, is transferred from Mauthausen to Sachsenhausen. Upon arrival, they are met by Sturmbannfuhrer Herzog—the very inspector who apprehended Sali five years prior. He reveals that their exceptional skills in forgery have earned them a role in "Project Bernhard," aimed at undermining the economies of both Britain and the USA through the mass production of forged banknotes.
The newcomers receive new attire, which is actually taken from other inmates, and one of the group, Adolf Burger, adamantly refuses to wear them. They are shown to their quarters featuring sprung beds and clean linens, starkly contrasting the horrific conditions experienced by other prisoners in the camp. The team is introduced to established members already working on the project, including the kapo and a Jewish German banker. Herzog appoints Sali as the team leader, directing them to focus on rapidly creating flawless pound note forgeries.
The narrative follows the development of these forgeries, highlighting Herzog's erratic behavior, shifting from affable to tyrannical, while the other camp guards remain unyieldingly brutal. Although glimpses of the overall camp's inhumane environment are shown, the forgers enjoy relative comfort. Eventually, Herzog is pleased with the completed pound forgeries, even going so far as to have them examined by both a Swiss bank and the Bank of England, who to his delight, authenticate them.
As the war nears its conclusion, Herzog announces that the production of dollar forgeries has become paramount. Tensions rise as one of the group develops tuberculosis, with no available treatment. Burger becomes increasingly vocal in his dissent regarding their involvement, threatening to sabotage the project. As arguments flare between Sali and Burger, they wrestle with moral questions: Should they cooperate for their own survival while prolonging the conflict? Should they indulge in comfort while their compatriots suffer just outside the camp's gates? Their predicament comes to a head during a game of table tennis when they hear the brutal beatings of fellow prisoners, and bullets fly dangerously close.
Ultimately, Herzog gives the group an ultimatum: produce the dollar forgeries or face execution for five of them. In desperation, Sali strikes a deal with Herzog to finish the work in exchange for medication for his ailing friend. They both keep their promises, but tragically, just before the treatment can be administered, Sali's friend is shot "to save them all from catching the disease." No sooner is the final dollar forgery completed than they are ordered to dismantle their operation and pack the equipment for safekeeping ahead of the approaching Allied forces.
As they finalize their tasks, they wake one morning to discover that all the German guards have fled. Sali confronts Herzog, disarming him, yet chooses to let him go rather than seeking vengeance. The following day, the wall of their compound is torn down, revealing a mob of prisoners from the rest of the camp, who threaten them. Their only salvation comes from displaying their tattooed camp numbers.
The film concludes back at the Monte Carlo casino where Sali impulsively risks all his winnings, followed by a whimsical moment on the beach with the glamorous escort from the casino. She console him over his losses as he responds with a confident, "We can soon make some more."
