The Shanghai Cobra is a 1945 mystery film directed by Phil Karlson and starring Sidney Toler as Charlie Chan.

[1][2] When three bank employees are killed with cobra venom, Detective Chan recalls an oddly similar case ten years earlier in Shanghai.

Chan has a second reason to be interested...the bank is the central depository for radium distribution for a good part of the United States.

Tommy Chan and Birmingham, usually against orders, spend a goodly amount of time prowling these tunnels.

Oddly, it is concealed behind a bookcase on the second floor of the bank building...in an office housing a full chemical laboratory.

Chief Bank Guard John Adams is revealed to be the escaped Jan Van Horn.