This is loosely adapted from a couple of Somerset Maugham's Ashenden spy stories; three British operatives in neutral Switzerland are detailed to assassinate a German agent before he leaves to meet contacts in the middle east. While Europe drifts towards another war.
Though it draws from contemporary anxieties, this is chiefly an Alfred Hitchcock comedy thriller, with a sliver of moral deliberation on the themes of war and espionage. There's a classic moment of visual commentary when the wrong man is murdered by Peter Lorre, viewed distantly by a morally passive John Gielgud through a telescope.
The main debit is a disinterested contribution by Gielgud as Richard Ashenden, who mysteriously fails to shine in the reflection of another feisty performance from a stunning Madeleine Carroll. The German double agent played by Robert Young shares far more chemistry.
It's fine entertainment, with many characteristic touches from the Master, inventive use of sound, some invigorating visual flourishes. And a thrilling climax when the train leaves Switzerland to expose the British spies to sudden danger without the protection of neutrality.