So "Charlie" (Warner Oland) is to be the guest of honour at a grand banquet. That's all going fine until a prominent British diplomat "Sir Stanley" (David Torrence) finds that his planned gift to our honourable detective is quite lethal... Together with No. 1 son "Lee" (Keye Luke) they must discover whether it was he, or the diplomat, who was the target of their assailant. It doesn't take them long before they, together with local police commissioner "Col. Watkins" (Halliwell Hobbes) and an American agent "Andrews" (Russell Hicks) stumble upon an opium smuggling caper that might just involve…