In southern France during the Roaring Twenties, Philip Bang, Anthony Quinn, a notorious master con man, is being relocated to a high-security facility for hard labor after causing an uproar at supper. This move is actually part of a larger scheme to spring him from prison, arranged with the aid of his former wife and partner, Belle Duke (a casino yacht proprietor and herself a con artist), and his daughter, Charlotte. The plan rolls forward as Bang is en route to a transit facility, and at the moment of stepping out to a wagon restroom, he unexpectedly becomes an unwilling escape accomplice to another con man, the young Italian Felix, who quickly leaves Bang in the lurch.
Before Felix can enjoy his newfound freedom, Belle Duke’s men grab him, mistaking him for Bang. Once her team learns the truth, Belle Duke insists that Felix free Bang. Felix manages to slip away from her thugs, but Belle Duke uses Charlotte to set a trap, leaving Felix with little choice but to agree to her demands. Drawing on his own experience with the transit system, a purloined priest’s cassock, and a cuckoo clock bomb, Felix orchestrates Bang’s breakout. Yet Bang is reluctant to return to Belle Duke, not least because he has previously fleeced her of her wealth and now fears her vengeance.
As the pair test Felix’s skills and attitude, a fragile trio forms: Bang, Felix, and Charlotte. Charlotte has fallen in love with Felix, which adds a personal layer to the volatile partnership. Bang decides to test Belle Duke once more by staging a grand deception: they use the money they’ve scrambled together to buy a seemingly worthless swampland, presenting it as a genuine archeological sensation. The ruse relies on real museum exhibits and Bang’s old gang to lend an air of legitimacy, while a supposed black market scheme is pitched to persuade Belle Duke to pay an astronomical price for the land.
The plan momentarily ascends to a higher stakes bluff when Felix raises the ante by claiming that he has kidnapped Charlotte, exploiting Bang’s genuine distress to persuade Belle of the authenticity of their con. Felix then makes a dash with the ill-gotten funds, and is believed to have perished when his escape boat crashes into a boathouse and explodes. Soon after, the police, alerted by Felix as part of the ruse, arrive to arrest Bang. However, the supposed arrest is revealed as another layer of the deception: the police squad is Bang’s own con gang, and a motorcycle escort turns out to be Felix commanding a handful of shop-window mannequins.
After convincing Bang that the kidnapping pretense was merely a maneuver to mislead their rivals, the trio—Bang, Felix, and Charlotte—narrowly escape Belle Duke via a single-engine airplane. In a final gambit, Felix cannot resist one last flourish: when an open door scatters the fleeced 100 million Francs, he theatrically lets them spill out, only to reel them back in, each bill tied to a long line, restoring their control over the fortune and sealing their escape with a last triumphant bluff.
