Phantom of Chinatown (1940)

In the middle of a pictorial lecture on his recent expedition to the Mongolian Desert, Dr. John Benton the famous explorer, drinks from the water bottle on his lecture table, collapses and dies. His last words "Eternal Fire" are the only clue Chinese detective Jimmy Wong and Captain Street of the police department have to work on. Win Lee, Benton's secretary, reveals the doctor's dying words refer to a scroll which tells the location of rich oil deposits. Wong and Street then begin the search for the killer among Benton's associates.