A pretty Chinese woman, seeking help from San Francisco detective James Lee Wong, is killed by a poisoned dart in his front hall, having time only to scrawl "Captain J" on a sheet of paper. She proves to be Princess Lin Hwa, on a secret military mission for Chinese forces fighting the Japanese invasion. Mr. Wong finds two captains with the intial J in the case, neither being quite what he seems; there's fog on the waterfront and someone still has that poison-dart gun...

Directed by: William Nigh
Written by: Scott Darling
Runtime: 71 minutes
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Cast:
Boris Karloff Boris Karloff
Mr. James Lee Wong 
Marjorie Reynolds Marjorie Reynolds
Roberta 'Bobbie' Logan 
Grant Withers Grant Withers
Police Capt. Bill Street 
Huntley Gordon Huntley Gordon
Mr. Davidson 
George Lynn George Lynn
Capt. Guy Jackson 
William Royle William Royle
Capt. Jaime