Secret Agent X-9 (1937 serial)

Secret Agent X-9 (1937) is a Universal film serial based on the comic strip Secret Agent X-9 by Dashiell Hammett and Alex Raymond. == Plot == G-Men learn that "Victor Brenda", a notorious jewel thief, is heading for the US, to steal the Belgravian crown jewels currently on exhibit.

Source: Wikipedia — Secret Agent X-9 (1937 serial) (CC BY-SA 4.0)