Stamboul Quest is a 1934 American spy film set in World War I, directed by Sam Wood, starring Myrna Loy and George Brent and featuring Lionel Atwill.

She also informs von Sturm that fellow spy Mata Hari has fallen in love with her assigned target and can no longer be trusted.

When Kruger is arrested at his dentist contact's office, another patient, Douglas Beall, an American studying medicine in Germany, is also taken into custody.

To gain his trust, she arranges for Beall to be framed as a spy by von Sturm (who has arrived after becoming concerned by Karl's reports) and supposedly executed by firing squad, though a French prisoner is to be substituted.

When von Sturm admits that he was unable to make the switch and that Beall really was shot, Helena loses her sanity and is confined in a nunnery.

The story in Stamboul Quest is based on an actual person, a German-trained spy in World War I named Annamarie Lesser – as in this film – or possibly Elsbeth Schragmüller who used the code name "Fräulein Doktor" – probably referring to the PhD she held from the University of Freiburg – and who ran a training school for espionage agents in Antwerp, Belgium during the German occupation of the city.

According to Myrna Loy's autobiography, the studio was particularly careful about how the script portrayed Fräulein Doktor, since at the time the film was made she was still alive, and a drug addict, living in a sanatorium in Switzerland, and they were concerned about being sued for libel.