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 lonver mais...