The Chinese Ring (1947)

Princess Mei Ling pays a visit to the Chan residence, where upon being admitted by man-of-all-work Birmingham Brown she refuses to give her name, but hands Birmingham her ring to show to Charlie. While Chan is being summoned, a mysterious figure shoots a dart at the beautiful Princess who manages, before she dies of poison, to scrawl the name "Captain K" on a handy piece of paper.

When the police arrive, Charlie has to admit that he does not know the identity of his murdered visitor, but that he means to find out. What he learns is that Mei Ling has brought with her to America the sum of one million dollars, in order to buy airplanes for the Chinese struggle for freedom. Someone has stolen the money, and someone may be trying to divert the planes into enemy hands. Can the famous detective, despite the fact that his Number Two Son has unaccountably changed his name from Jimmy to Tommy, who used to be his Number Three son, and despite the fact that Charlie, who used to be a Honolulu Police Detective, and then a Honolulu Police Detective On Loan To The United States Secret Service, has not only lost his jobs, but also the rest of his large family and has moved to San Francisco, discover who the bad guys are and solve the case?