Actor Patrick Macnee leads the viewer through London in the footsteps of the genius private investigator Sherlock Holmes and his assistant and friend, Dr. Watson.

The evolution of Holmes on screen, from silent movies to new TV versions, with contributions from Sherlock's past and present.

Arthur Conan Doyle reveals the story behind Sherlock Holmes and his mysteries by telling about Dr. Joseph Bell, from whom he drew his inspiration, after meeting him as a medical student in Edinburgh. This TV movie served as the pilot for the later released minisseries Murder Rooms: Mysteries of the Real Sherlock Holmes produced by the BBC. The series then picks up with Sir Arthur Conan Doyle's time as a general practitioner in Southsea, solving mysteries with the help of his mentor, Dr Joseph Bell, who is still based in Edinburgh.

In the midst of World War II, Sherlock Holmes rescues the Swiss inventor of a new bomb-sight from the Gestapo and brings him to England, where he quickly falls into the clutches of the evil Professor Moriarty.

Having once again avoided criminal conviction, Professor Moriarity develops a murderous plan to “finish off” his last major nemesis, Sherlock Holmes, by making him fail to prevent the perfect crime. Does it involve a family curse, the crown jewels of England, or something else…

In a mansion full of secret rooms and passageways, people are dying shortly after seeing the ghost of a woman in gray, as an old legend dictates. Called in to solve the mystery, Sherlock Holmes has doubts about the supernatural aspect of the crimes and focuses on a more earthly culprit.

Sherlock Holmes has retired. But when MacDonald asks him to take on another case, he says yes. There have been some mysterious murders, and there are no visible causes for the deaths. At the same time Holmes gets this case, Graf Udo Von Felseck gives him another case: find a young and missing prince to prevent war between Germany and England. But Von Felseck is not as honest as he seems...

Now a detective-for-hire like her infamous brother, Enola Holmes takes on her first official case to find a missing girl, as the sparks of a dangerous conspiracy ignite a mystery that requires the help of friends — and Sherlock himself — to unravel.

When Watson reads from the newspaper there have been two similar murders near Whitechapel in a few days, Sherlock Holmes' sharp deductive is immediately stimulated to start its merciless method of elimination after observation of every apparently meaningless detail. He guesses right the victims must be street whores, and doesn't need long to work his way trough a pawn shop, an aristocratic family's stately home, a hospital and of course the potential suspects and (even unknowing) witnesses who are the cast of the gradually unraveled story of the murderer and his motive.

Sherlock Holmes and Dr. Watson embark on a search for Cleopatra's ancient necklace, which has been stolen.

England, at the start of World War Two. Mysterious wireless broadcasts, apparently from Nazi Germany are heard over the BBC. They warn of acts of terror in England, just before they take place. Baffled, the Defense Committee call in Sherlock Holmes.

When a nobleman is threatened by a family curse on his newly inherited estate, detective Sherlock Holmes is hired to investigate.