Charlie is called in to help a mine owner Mr Manning (Forrest Taylor) who is in danger. The mine, supposedly all spent, is also producing a mysteriously large amount of ore. Manning is badly injured in an accident and Chan (who is posing as a curio trader) investigates the case for Manning's daughter Evelyn (Wanda McKay).
Chan is helped (in theory) by his Number Two son Tommy (Victor Sen Yung) and chauffeur Birmingham (Mantan Moreland). The police in the form of Lt. Ruark (Tim Ryan) is also on the case.
As a mystery it is fairly serviceable. Winters didn't have the same spark as the earlier actors who played the role and the film lacks the wit of earlier entries in the series. The story plods somewhat but has some surprises in store for the patient.
