June, 1944. Six allied commandos spying on Japanese ship movement fall under threat when their covert operation is discovered by the enemy. Stuck in the jungles of occupied Borneo, the only hope for rescuing them is USS Harder, an American Gato Class submarine. To save the operatives, Commander Sam Dealey and his crew ply through waters guarded by a key Japanese Naval base, an act that pits the single submarine against dozens of warships. The daring rescue puts USS Harder's strength and stealth to the test.