In the Straits of Sembaleng, five men are dispatched by submarine in Klepper canoes to rescue survivors of a shot-down plane on a nearby island occupied by the Imperial Japanese Army. Led by Captain Kelly, Mel Gibson, an inexperienced commando officer, the team secretly lands on the island and hides their kayaks. As they venture inland, Ted 'Kingo' King, John Waters, is hit by fire from an unseen machine gun post, and the four remaining men swiftly neutralize the Japanese defenders and rush back to their wounded comrade. King has been struck in the leg, the bullet smashing his kneecap. He cannot be allowed to fall into enemy hands and jeopardize the mission under interrogation, and after sharing a cigarette with him, Costello Sam Neill shoots him. The four survivors resume their search and come across a rice farmer, learning of the area where the plane crashed; the farmer is killed to preserve secrecy.
As they near their destination, they spot a Japanese squad at a local house. After the Japanese depart, they enter and meet the local resistance leader Lin Chan-Lang Ko Chun-Hsiung and his grown-up daughter Chien Hua Sylvia Chang along with her younger brothers and sisters. With a guide to lead them, they press on toward the plane but are attacked by Japanese soldiers at a Buddhist temple. Separated from the others, interpreter Jan Veitch John Phillip Law ends up returning to Lin's house, where Chien Hua hides him from the returning Japanese. After the deaths of their own soldiers, the Japanese officers Watanabe and Imanaka torture Chien to reveal the location of Lin, whom they believe is sheltering the survivors, but Chien Hua refuses. Lin's son Shaw Hu falsely tells the Japanese that Lin, the Z men, and the plane's survivors are heading for the island's capital. All the Japanese depart except for two soldiers guarding Chien Hua; Veitch kills both with Shaw Hu’s help. During the fighting, Costello is wounded in the arm and cornered by a machine gunner, and he tosses a grenade at the gunner but is shot and killed in the process.
Meanwhile, within sight of the plane, Kelly watches as locals blow up the wreckage. Lin is evasive, and after questioning the inhabitants of a village, the team continues toward the plane. Kelly manages to extract that the two survivors are being taken to Lin’s home, so they turn back. In the capital, Veitch is led to the survivors. One of them is a defecting Japanese government official Imoguchi, who is believed to hold a secret that could hasten the end of the war. Only Kelly understands that he must be rescued at any cost—or killed. As the pieces of the puzzle come together, Kelly must persuade his own men that Imoguchi is worth saving and the local resistance that it is worth fighting against their Japanese adversaries.
