AllMovie

The Castaways are certain that a new war has begun and that they're in the thick of the fray. The reason? An unseen assailant is bombarding the island with hand grenades. Almost immediately, the Skipper (Alan Hale Jr.) organizes the Castaways into an emergency army--little suspecting that the hand lobbying the grenades belongs to a gorilla, who has come across a cache of leftover WW2 weaponry!