An aging actress living in her Hollywood mansion with a retinue of elderly servants employs a new, mentally disturbed, personal assistant who schemes to take over the large estate.
Nagata escapes from a mental institution, thinking it is December 1941. He had been part of a group called Black Dragons, a Japanese group that engaged in "fifth column" activities. Nagata upon escaping kills a guard, steals dynamite and constructs a time bomb. It turns out Nagata was supposed to blow up a fuel-storage facility at Pearl Harbor. McGarrett & Co. race to stop Nagata who also has his grown daughter, who he has mistaken for his wife, as a hostage.