After exposure to radiation, an atomic research scientist finds himself changing into a murderous, lizard-like creature every time he is exposed to sunlight.

Posing as an ex-German medical officer, a U. S. Navy Intelligence Officer sets out to rescue a kidnapped scientist, and sink a Nazi submarine, hiding off the coast of South America.

In occupied Berlin, a US Army Captain is torn between an ex-Nazi cafe singer and the US Congresswoman investigating her.