Holmes is commissioned by a mysterious client, 'one of the most exalted in the land,' to free a beautiful girl from the clutches of a dangerous criminal. It proves to be a hazardous operation for all concerned...

"Yes, Watson - madness and death." These are the dangers to which the great detective and his friend are exposed in solving the mystery of diabolic happenings in remote Cornwall. As the story unfolds in these bleak surroundings, we may wonder who is the more dangerous man: Patrick Troughton’s weaselly Tregennis or Carl Bernard’s imperious Sterndale – both powerful performances.

When a beautiful young woman is threatened by unknown dangers in a remote country house, Holmes and Watson are quick to fly to her aid. Suzanne Neve’s authentic portrayal of Violet Hunter as ‘a very brave and sensible girl’ is not overshadowed by Patrick Wymark’s bravura performance as Rucastle, whose joviality masks a cruelty, tellingly revealed in his smiling approval of his child’s brutality towards small animals. It is just one of many excellent touches in Vincent Tilsley’s adaptation.

Jabez Wilson is a struggling pawn broker hardly worth the attentions of any petty thief. But when Wilson loses a job that is both ludicrous and lucrative, Holmes realises that he is the victim of a master criminal.

Daringly, Cooper dramatised this tale of robbery, murder and revenge as a comedy. James Bree, is priceless as the Napoleon-obsessed Barnicot. The depictions of the distrustful Browns and the self-regarding Horace Harker are not far behind, but none of the story’s excitement and ingenuity is sacrificed to the humour. The real joy of this episode is the introduction of the lantern-jawed Peter Madden as a sardonic, capable Inspector Lestrade.

There’s much to enjoy in this episode, including the fine performances of Anton Rodgers and Anna Cropper, and especially the genuine East End locations. The dilapidated riverside buildings we see here would be unrecognisable today. Curiously, Jan Read’s script relocates Watson’s discovery of Holmes at the opium den to the wrong point in the story, rendering the detective’s need for heavy disguise rather pointless.