A young drifter named Joe, with no memory of his past, finds himself conscripted into the U.S. Army in the Philippines. During a convoy mission, the unit is ambushed by rebels working with a mysterious ninja sect. Displaying exceptional martial arts skills, Joe single-handedly fends off the attackers, impressing his comrades but also drawing suspicion and scrutiny from his superiors. His extraordinary abilities catch the attention of his fellow soldier Curtis, who becomes both a friend and ally. Meanwhile, Patricia, the general's daughter, is kidnapped during the ambush, and Joe's heroics in rescuing her further complicate his already precarious standing within the army.

As Joe and Curtis delve deeper into the mysterious attacks, they uncover a sinister plot involving a corrupt local businessman running an arms smuggling operation with the aid of a secret army of ninjas. Joe gradually starts to recover flashes of his past, revealing that he was trained by a Japanese master in the ways of the ninja. Despite being reprimanded and distrusted by certain army officials, Joe and Curtis decide to take matters into their own hands to dismantle the criminal operation. They face increasingly dangerous confrontations with highly skilled adversaries as they attempt to thwart the looming threat.