Captain Terence Stevenson, a British soldier fluent in Rumanian and German, attempts to sabotage a German poison-gas factory by going undercover. He becomes "Jan Tartu," a member of the Rumanian Iron Guard. But when his contacts are destroyed, his disguise may get him killed by the very underground group he needs to succeed! Robert Donat, Valerie Hobson, and Glynis Johns star in this tale of action and intrigue from director Harold S. Bucquet (Dragon Seed, Without Love).