 Karl Schindler, a former Nazi officer who ran a concentration camp during World War II, is now a Communist spy. Otto Mann, a Nazi hunter, nearly arrests Schindler on a cruise ship headed to New York. Mann is a friend of Erskine and wants to assist the FBI. But Mann s wife died at Schindler s concentration camp. Erskine is uncertain whether Mann will attempt to gain personal revenge; the FBI man wants to capture Schindler alive for his knowledge of U.S.-based agents.