Captain Hugh "Bulldog" Drummond is, yet again, all set to wed his long-suffering fiancée Phyllis Claverling (Heather Angel). And, yet again, the wedding must wait when the eccentric Professor Downie (Forrester Harvey) appears. The Professor informs Bulldog that a fortune is buried on the Rockingham estate where he is to get married and he has the secret cipher that will lead them to it. Before he can follow through, the Professor is murdered, and the hunt is on to find the killer and the hidden treasure.