Mr. Moto battles murderous treasure hunters for priceless ancient scrolls which reveal the location of the long-lost tomb of Genghis Khan.

A man sneaks into a tent to steal a scroll, but adventurer and soldier of fortune Kentaro Moto (Peter Lorre) is only pretending to be asleep and kills him.

He changes clothes and accepts an invitation to a party hosted by Colonel Tchernov (Sig Rumann) in honor of American Eleanor Joyce (Jayne Regan).

At the soirée, Moto observes a guest, Prince Chung (Philip Ahn) leaving his mother to speak privately with Tchernov in another room.

Schneider (Wilhelm von Brincken) holds him at gunpoint and forces Moto to give him the scroll.

However, the gun was filled with blanks and Moto trails Schneider to Madame Tchernov (Nedda Harrigan).

When they leave to rendezvous with their gang, Moto starts to follow, but is knocked out by the butler, Ivan (John Bleifer).

The arch-villain (and Madame Tchernov's lover), Herr Koerger (Sidney Blackmer), forces Prince Chung to reveal the location of the scrolls by striking his mother.

Then he sows dissent by telling Madame Tchernov that Koerger is actually in love with Joyce, which the quick-thinking American "confirms".

[8] By now the films were so popular that in December 1937 Fox refused Lorre a leave of absence to appear on Broadway in Wine of Choice with Miriam Hopkins.