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.
| Actor | Role |
|---|---|
 Jeremy BrettSherlock Holmes | Sherlock Holmes |
 Edward HardwickeDr. John Watson | Dr. John Watson |
 Jenny SeagroveMary Morstan | Mary Morstan |
 Ronald LaceyThaddeus und Bartholomew Sholto | Thaddeus und Bartholomew Sholto |
 John ThawJonathan Small | Jonathan Small |
 Emrys JamesInspector Athelney Jones | Inspector Athelney Jones |
 Alf JointMcMurdo | McMurdo |
 Kiran ShahTonga | Tonga |
| TTerence SkeltonCaptain Morstan | Captain Morstan |
 Rosalie WilliamsMrs. Hudson | Mrs. Hudson |
 Robin HunterMajor Sholto | Major Sholto |
 William AshJack Smith | Jack Smith |
| IIshaq BuxLal Chowder | Lal Chowder |
 Derek DeadmanWilliams | Williams |
| MMarjorie SudellMrs Bernstone | Mrs Bernstone |
| GGordon GostelowSherman | Sherman |
 Lila KayeMrs Mordecai Smith | Mrs Mordecai Smith |
| CCourtney Roper-KnightWiggins | Wiggins |
| TTommy WrightBoatyard Workman | Boatyard Workman |
| DDave AtkinsMordecai Smith | Mordecai Smith |
 Badi UzzamanKartar Singh | Kartar Singh |
 Renu SetnaAchmet | Achmet |
| RRavinder Singh ReyettJagodish Singh | Jagodish Singh |