Mary Morstan has received a pearl in the post every year since her father's disappearance. This leads Holmes and Watson to the truth about a secret pact between four convicts during the Indian Rebellion of 1857.

Jeremy Brett
as Sherlock Holmes

Edward Hardwicke
as Dr. John Watson

Jenny Seagrove
as Mary Morstan

Ronald Lacey
as Thaddeus und Bartholomew Sholto

John Thaw
as Jonathan Small

Emrys James
as Inspector Athelney Jones

Alf Joint
as McMurdo

Kiran Shah
as Tonga

Terence Skelton
as Captain Morstan

Rosalie Williams
as Mrs. Hudson