Ray, a writer struggling for a plot, receives an unexpected visit from an old acquaintance named Porky Jenks. Porky is terrified and on the verge of a breakdown because his consciousness has started detaching itself from his physical body, allowing him to involuntarily usurp the minds of unsuspecting strangers. After demonstrating this uncanny gift by temporarily taking control of an old woman at a street corner and causing minor city chaos, Ray and his friend Baldy immediately recognize its potential strategic value. With World War II raging and German U-boats lurking off the American coast, they hatch a plan to use Porky's ability to infiltrate enemy submarine commanders and sink the Axis fleet.
Despite Porky's protests and the moral objections of Ray’s daughter Lisbeth, the group travels to a lonely stretch of beach that night to test the plan. When Porky projects his mind into the sea, however, the results far exceed their expectations. Instead of a mere submarine, Porky accidentally channels a colossal, barnacle-encrusted green giant towering hundreds of feet out of the ocean. Coincidentally timed with an air raid by Nazi bombers, the massive creature violently swats enemy planes out of the sky before being struck by torpedoes and vanishing beneath the waves.
Following this narrow escape, Ray and Baldy map out an ambitious campaign to use the giant to turn the tide of the entire war. However, their plans are abruptly derailed when Porky and Lisbeth return from a romantic evening together with surprising news. Porky has fallen deeply in love and, as a result, has permanently lost his strange psychic affliction. With his ego now safely anchored to Lisbeth, the superpower is gone forever, leaving Ray and Baldy to accept that the war will have to be won the hard way.
