Drummond's wedding with Phyllis is interrupted when the inspector guarding their gifts is killed. He tries to trace the killers and uncovers the mystery of diamond counterfeiters.
John Barrymore
as Colonel Neilson
John Howard
as Captain Hugh 'Bulldog' Drummond
Louise Campbell
as Phyllis Clavering
Reginald Denny
as Algy Longworth
E. E. Clive
as Tenny
Porter Hall
as Dr. Botulian
Elizabeth Patterson
as Aunt Blanche
Nydia Westman
as Gwen Longworth
Halliwell Hobbes
as Prof. Bernard Goodman
Matthew Boulton
as Sir Raymond Blantyre
Zeffie Tilbury
as Mrs. Weevens
David Clyde
as Constable McThane
