During World War II, a schoolteacher turned Dutch resistance fighter, Vincent Van Der Lyn, Paul Henreid, becomes a thorn in the Nazi regime to such an extent that a bounty is placed on his head. He is ordered by his superiors to slip from occupied Europe to England via the neutral port of Lisbon, setting in motion a perilous journey that tests nerves, loyalties, and the odds of survival.
On his arrival, Police Captain Pereira, Joseph Calleia, notices that Van Der Lyn’s passport bears no exit stamp, a sign he appears to have slipped across the border. Yet Pereira remains pragmatic, accepting that the Portuguese visa is in order and that the mission’s success hinges on discretion. Across the city, German agent Otto Lutzke, Kurt Katch, grows suspicious, tails the Dutchman, and reports back to his superiors in a tense game of cat and mouse that could spark a dangerous confrontation at any moment.
A restaurant encounter becomes a turning point. Irene Von Mohr, Hedy Lamarr, sits down at Van Der Lyn’s table after discreetly signaling a man in an alley with a card that is quickly followed by a shot. She bolts into the restaurant to throw off pursuit, feigning nothing more than a gambler’s routine at the Casino Estoril. When Van Der Lyn follows her lead, he discovers Irene at the casino, where she warns him to stay away, only to be drawn further into a shadowy world of espionage that includes Hugo Von Mohr, a high-ranking German diplomatic official, and Lutzke, who soon close in on him. Hugo’s presence signals a dangerous alliance between the Nazi machinery and their inside men, complicating Van Der Lyn’s precarious position as he becomes a target of a sophisticated network.
The Nazis quickly identify the Dutch saboteur, nicknamed the “Flying Dutchman,” and the plot widens to include a small, disciplined resistance group led by Ricardo Quintanilla, a determined organizer who introduces Van Der Lyn to Jan Bernazsky, a skilled Pole, Anton Wynat, a Norwegian operative (uncredited in the film), and the Frenchman Paulo Leiris. Quintanilla also asks Van Der Lyn to brief Jennings, his eventual replacement, underscoring the fragile chain of trust within the resistance. In private, Quintanilla warns that one among them may be a traitor, casting a pall over the group’s unity as they navigate a web of deception.
The next day, Irene reappears in Van Der Lyn’s life, and the two share a ride that deepens their bond. He confesses love for her, and she reveals a storied past: she married Hugo after he rescued her from the Dachau concentration camp. The romance complicates the political stakes, and as the pair drift closer together, Irene’s loyalties and true motives become increasingly uncertain.
Back at his hotel, Van Der Lyn’s world is jolted when Jennings, his ally and contact, is found dead at his desk. The police arrest Van Der Lyn for Jennings’s murder on a false tip, and Irene defends him to Captain Pereira, insisting that he was with her all day but refusing to testify. In a desperate turn, Van Der Lyn escapes, and Irene helps him reach Quintanilla and the others, explaining that she is also part of the resistance. Despite his suspicions about Irene, the pair’s shared danger keeps them aligned as they search for the truth behind Jennings’s dying message.
The group’s suspicions converge on Hugo, whose duplicity becomes clear when the dying message hints that someone has taken the “eagle”—a rare coin used as an identifying signal. Quintanilla decides to bait the trap by announcing that Jennings’s replacement is in the casino hotel, knowing that the Germans will move to seize him and plant their own agent. Pereira spots Van Der Lyn but is persuaded to wait for the true killer to surface. With minutes to spare and the atmosphere thick with tension, Quintanilla shares the room number, 865, with the group, counting down to the moment when the traitor will reveal himself.
As the roulette wheels spin and the casino hums with subtle danger, Hugo places bets on 8, 6, and 5—the exact digits that betray him as the traitor. The revelation is swift and decisive: Hugo is unmasked and taken away by Quintanilla and the resistance, though he manages a desperate escape before meeting a final, fatal confrontation in a high-stakes pursuit through the casino. In the end, the eagle is found tucked in Hugo’s pocket, sealing the traitor’s fate.
With the network of danger dismantled, Vincent Van Der Lyn makes a bold decision—he will return to occupied Europe in Jennings’s place, fulfilling a mission that was never merely about escape but about striking a repair to the fragile thread of resistance. Irene promises to wait for news of his safe passage, and Vincent offers a silent pledge to return, a vow forged in the gravity of sacrifice and the unspoken trust built between unlikely allies.
