7. Charlie Chan at Treasure Island (1939)
Beginning with a seemingly impossible death on an airplane, and followed by a fabulous mystery set against the backdrop of the occult during the Golden Gate International Exposition, Sidney Toler's third time as Charlie Chan was also his finest. The identity of the killer is superbly concealed until the final moments, thanks to an exquisite script by John Larkin. Toler himself was never better. Witness the anguish on his face when he finds himself tasked with breaking the news of a friend's death to the man's wife. It's rumoured that the real-life Zodiac killer took his name from a character in this film.
Chan: "If befriend donkey, expect to be kicked"