Background to Danger is a 1943 World War II spy thriller film starring George Raft and featuring Brenda Marshall, Sydney Greenstreet, and Peter Lorre.

Based on the 1937 novel Uncommon Danger by Eric Ambler and set in politically neutral Turkey, the screenplay was credited to W. R. Burnett, although William Faulkner and Daniel Fuchs[2] also contributed.

The Russian operative positively portrayed by Brenda Marshall shows an exaggerated degree of cooperation,[3] and the film has a slight pro-Soviet bias akin to Warners' Mission to Moscow from the same year.

Much to the annoyance of Colonel Robinson (Sydney Greenstreet), von Papen survives and the Russians that his agent provocateur was trying to frame have solid alibis, forcing him to turn to another scheme to inflame Turkey's traditional rivalry with Russia.

American machinery salesman, Joe Barton, (George Raft) boards the Baghdad–Istanbul Express train at Aleppo and is attracted to another passenger, Ana Remzi (Osa Massen).

Worried about being searched by customs agents once they reach the Turkish border, she asks Joe to hold on to an envelope containing some securities, all that remains of her inheritance.

He watches unobserved as Soviet spy Nikolai Zaleshoff (Peter Lorre) searches the dead woman's luggage.

Leaving the scene, he is seen by Tamara Zaleshoff (Brenda Marshall), Nikolai's sister and partner in espionage.

There, Robinson has bribed a newspaper publisher to print an article claiming that the documents are secret Russian plans for the invasion of Turkey.

[10][11] Raft insisted on the script being changed so that his character was an undercover American agent instead of an ordinary man.

The point of Background to Danger was that this man was a salesman and suddenly things begin to happen to him that he can't understand.