During the Nazi uprising in 1939, they have captured prominent Czechoslovakian scientist Axel Bomasch and his adult daughter Anna Bomasch. Despite the senior Bomasch having escaped to England before the Nazis invaded Czechoslovakia, the Nazis were able to discover his hiding location in part due to an elaborate ruse using Anna, who at the time was imprisoned in a concentration camp, and Karl Marsen, a Gestapo officer posing as a fellow camp prisoner. Dickie Randall, an English officer using the code name Gus Bennett, decides to mount his own rescue of the Bomasches posing as a S.S. major. Anna feels she has no other choice but to go along with whatever Bennett tells her in an effort to escape from the Nazis, despite she not fully trusting him due to his seemingly cavalier attitude. Bennett and the Bomasch's ability to escape may be placed into jeopardy by two Englishmen traveling on the same night train to Munich

In the midst of Nazi air raids, a postman dies on the operating table at a rural hospital. But was the death accidental?

On a train headed for England a group of travelers is delayed by an avalanche. Holed up in a hotel in a fictional European country, young Iris befriends elderly Miss Froy. When the train resumes, Iris suffers a bout of unconsciousness and wakes to find the old woman has disappeared. The other passengers ominously deny Miss Froy ever existed, so Iris begins to investigate with another traveler and, as the pair sleuth, romantic sparks fly.