In 1942, shortly after the bombing of Pearl Harbor, John Royer, an ex-newspaper correspondent, is summoned home by his publisher, John Manchester, after serving four years in the Far East.  When Manchester asks Royer to help in a nation-wide drive to salvage rubber, the reporter scoffs and proposes a daring scheme to smuggle large quantities of rubber out of Japanese-occupied Malaya.

After returning to his hotel room, Royer is contacted by a federal agent named Kellar, who reveals that he has thoroughly investigated Royer's past and has learned that Royer's story about smuggling resulted in the imprisonment of his friend Carnahan.  Later, Kellar escorts Royer to a railroad car where Manchester is waiting with a panel of men, who intend to question him about his plans.  Royer explains that he requires gold to buy the rubber, men needed to steal it and a camouflaged Navy ship to transport it from Malaya.  Royer also insists that Carnahan be freed from Alcatraz to work on the mission.  Carnahan is still angry at Royer for writing the expose that led to his imprisonment, but agrees to cooperate in return for his freedom.

As Royer and Carnahan set sail for Malaya, Royer explains that he is risking his own life because his brother was killed by the Japanese.  The cynical adventurer Carnahan responds that his only interest is in the gold.  Upon reaching the Malay city of Penang, Carnahan and Royer pose as Irish seamen and visit the saloon owned by the Dutchman, an old friend of Carnahan's.  There, Carnahan is warmly embraced by his former lover, the opportunistic singer Luana.  The Dutchman also introduces them to Col.  Genichi Tomura, the corrupt Japanese commandant with a penchant for gambling.  After hearing their plans, the Dutchman agrees to recruit twelve men for the operation.  While alone with Carnahan later that night, Luana recalls their past relationship and begs him to get her out of Malaya.

The next morning, the Dutchman puts Carnahan and Royer in touch with three of the biggest planters in the district.  Although all three agree to cooperate, Carnahan and Royer are wary of the third, Bruno Gruber, a German planter.  That evening, while Carnahan distracts the Japanese by getting himself arrested, Royer, aided by Romano and the other guerillas, delivers the rubber from the first two plantations to a U.S. ship camouflaged as a small island.  Afterward, the Dutchman convinces Tomura to release Carnahan into his custody.  Afraid to trust the German, Carnahan refuses to participate in the last shipment but Royer, out of revenge for his brother's death, insists on completing the mission.  Carnahan relents and joins Royer, then beats Gruber into revealing that the Japanese are waiting downstream to ambush them.

Determined to secure the last of the rubber, Royer continues on alone and is brutally killed by Tomura's men.  Hearing the sound of gunfire that signals the death of his friend, Carnahan shoots Gruber, prompting the Dutchman to observe that at least Royer died for his beliefs.  The following day, Tomura visits the Dutchman and offers to allow the remaining rubber to be shipped out for a price.  Although he suspects a trap, Carnahan resolves to complete Royer's mission.  While Romano and his men deliver the rubber, Carnahan decoys Tomura with his boat.  When Luana insists upon joining him, he pushes her overboard to safety.  As Carnahan nears the U.S. ship, Tomura stops his boat, takes him captive, then signals the Japanese flotilla to attack the ship.  Just then, two American PT boats suddenly appear and sink the flotilla with torpedoes.  In the fracas, Carnahan is wounded but manages to kill Tomura.

Some time after the end of the war, Kellar comes to Malaya to award a medal to Carnahan, who is now living on an island with Luana.  Refusing the medal, the cynical Carnahan tells Kellar to pin it on the Dutchman instead.