Thirteen-year-old Nick and his slightly dense older brother Herbert run the Diamond Private Detective Agency above Camden Town Tube Station in north-central London. When a master criminal called The Falcon dies, they come into possession of his box of chocolate Maltesers, which contains the secret key to a fabulous cache of diamonds. Can they unravel the mystery and avoid the clutches of seedy lowlifes Brenda Von Falkenberg, Gott and Himmell, The Fat Man and the dogmatic Chief Inspector Snape, all of whom want to find the swag first.
Dursley McLinden
Tim Diamond
Susannah York
Lauren Bacardi
Saeed Jaffrey
Mr. Patel
Patricia Hodge
Betty Charlady/Brenda von Falkenberg
Roy Kinnear
Jack Splendide
Jimmy Nail
Boyle
Bill Paterson
Chief Inspector Snape
Michael Robbins
The Fat Man
Peter Eyre
Gott
Nickolas Grace
Himmell
Michael Medwin
The Professor
Forbes Collins
Henry von Falkenberg
Jim McManus
Hammett
Robert Bathurst
Vicar
Jenny Tomasin
Traffic Warden
Geraldine Muir
Granddaughter
Gerald Campion
Uncle Holly