After World War II, ex-soldiers trickle into French Saigon to join the Foreign Legion, among them American Whit Corbett and German Carl Reicher. Is Reicher really SS war criminal Martin Bruner, and is Corbett after him? Art dealer Van Ratten and nightclub chanteuse Lili Maubert are also more than they seem. Action scenes include anti-guerilla jungle warfare.

At the end of World War II, American intelligence agent Whit Corbett is assigned to locate the last remaining high-ranking Nazi official at large, Martin Bruener, of whom no photos exist. Tracking Bruener to French Indochina, Whit plans to go undercover in the French Foreign Legion, a favored retreat of former Nazis. On the train to Saigon he meets Mark Van Ratten, a German masquerading as a Dutch antique dealer, and Bruener, who claims to be Carl Reicher, a former Wehrmacht private. In Saigon, Van Ratten, suspecting Bruener's true affiliation, warns him that the Legion is ferreting out those enlistees suspected of SS connections and sends Bruener to a man who can remove his tell-tale SS tattoo. Later, at a bar frequented by legionnaires, Bruener runs into his former lieutenant, Erich Heindorf, and warns him not to reveal his identity. At the same club, Whit meets singer Lili Maubert, a French agent, who puts him in contact with his local superior, Colonel Mauclaire. Mauclaire gives Whit a photo of Nazi officers sitting with Bruener, whose back is to the camera, and in the military archives, Whit matches one of the men in the picture to legionnaire Heindorf. As the local revolutionaries are continually mounting guerrilla attacks against the French, both Whit and Bruener are accepted into the Legion without question. Meanwhile, Lili discovers that Van Ratten sells equipment and rifles to the guerrillas and helps plan attacks. When Whit learns that Heindorf wishes a transfer, he suspects Bruener may be nearby posing a threat and plans to interrogate Heindorf. Before he can do so, the legionnaires are assigned a mission during which they are ambushed and surrounded. When Heindorf attempts to flee, Bruener shoots him in the back, and the severely wounded Heindorf is carried off by the guerrillas. Whit arranges to get into the guerrilla camp to speak to Heindorf. Realizing that Whit is closing in, Bruener goes to Van Ratten for help in securing a passport and transportation out of Indochina. As payment Bruener offers part of the contents of a chest of tools made entirely of platinum. When Van Ratten reveals that he has recognized Bruener, Bruener kills him and attempts to escape. With Heindorf's confirmation of Bruener's identity, Whit intervenes and, after a bitter fight, has Bruener arrested. Back in Germany, Bruener is tried and executed, while Whit returns to his home state of Nebraska with Lili.