The Pearl of Death is an enjoyable entry in the series and it boasts the singular villain “The Creeper”, who proved to be such a popular character that he got two spin-off films of his own; The Brute Man and House of Horrors, the latter being the superior film of the two. The famous Borgia Pearl is the coveted jewel at the centre of this Sherlock Holmes tale, it's in the care of the British Museum until stolen by a certain Mr. Giles Conover; “This man pervades Europe like a plague, yet no one has heard of him”. In this clip, the resourceful and very able Naomi Drake receives a message from her boss Giles Conover as he languishes in a gaol cell.

Synopsis

The Pearl of Death opens with an elderly vicar chatting to Naomi Drake aboard a ferry bound for Dover. As they chat and he falls sleep, she slips away and steals the Borgia Pearl from its courier's cabin and hides it in the back of her camera. She returns to the vicar and asks him to take her camera through customs as he is very unlikely to be searched, claiming that she doesn't want her photographs ruined if a customs officer opens the camera.

After they've docked at Dover, Drake retrieves the camera from the vicar and bids him farewell. She meets her accomplice Giles Conover at the docks, whereupon he discovers the absence of the pearl. “You've been had, my dear, properly had.” he laments after finding a note from Sherlock Holmes in place of the fabulous jewel. Holmes had been disguised as the vicar, much to Drake's surprise but not so much to Conover's.

Back on familiar ground at 221B Baker St., Holmes explains that evening's events to Dr. Watson as he removes his disguise. Inspector Lestrade soon arrives and the three of them escort the famous pearl to the Royal Regent Museum, where it's to be put on public display. The pearl will be protected by a rudimentary electric alarm system, one that Holmes is very unimpressed with, so he proceeds to demonstrate its inadequacies by covertly disconnecting the wires in the curator's office, rendering it useless.

Giles Conover is working at the museum and has been eavesdropping on Holmes' conversation, so when Holmes disconnects the alarm wires, he locks them all in the curator's office and steals the Borgia pearl. Conover lets himself be caught shortly afterwards, but the pearl is not found on him. Arrested for 'window breaking' and placed in the cells for 48 hours, Conover manages to send a message. Lestrade spills gravy on himself while searching Conover's breakfast tray but fails to find the message.

Naomi Drake is working as a washer-upper in the cafe that supplies meals to the police prisoners. When she gets Conover's tray, she finds the message detailing what Conover did with the pearl on a plate that she's washing up. As Holmes and Watson eat their breakfast, Lestrade arrives to tell them that he's had to release Conover, and also informs them of an apparently motiveless murder. An elderly colonel, Horace Harker, was found with his back broken amid a pile of smashed china, and Holmes takes an immediate interest in the case.

Holmes, Watson and Lestrade go to the murdered colonel's home to search for clues amid the broken crockery. A rather irritable Holmes deduces that there's a motive to the crime, and the unusual method of murder points to the infamous Hoxton Creeper, known to be Conover's henchman but Lestrade is sceptical. Holmes asks for all the broken china to be sent to 221B Baker Street and when he and Watson are walking home, an attempt on their life is made by Conover's men.

Watson is updating his scrap book the next morning when a visitor drops by with a gift for Holmes, an rare book only to be opened by him. The book contains a spring-loaded knife and when Holmes arrives home and is about to open the book, tobacco smoke alerts his suspicions and he springs the trap from a safe distance. As Conover has now made two attempts to kill Holmes, he deduces that Conover is desperately trying to recover the stolen pearl so he can't know its exact location.

A murder of a little old lady soon occurs, almost identical to the one of Horace Harker. Her back is broken and she's surrounded by a litter of smashed china, Lestrade thinks it's the work of a monomaniac but Holmes knows better and again asks to have the broken china sent to him. Meanwhile, The Creeper kills his third victim and again, leaves him in a litter of broken china.

Holmes and Watson examine the fragments of broken pottery at Baker St. and discover the link in each case - a plaster bust of Napoleon. Conover had placed the pearl in the plaster bust somehow, so Holmes and Watson go to question the guard who apprehended him. Conover had quickly gone into G. Gelder's Ornamental Plasterer's workshop before the guard “made the pinch”. Holmes goes into the workshop and uses Watson to demonstrate that Conover had indeed hidden the Borgia pearl in one of six busts of Napoleon. Gelder tells Holmes the location of Amos Hodder, the vendor of the busts.

Holmes and Watson go to Hodder's art shop, where they discover that Conover's accomplice Naomi is working there as an assistant. Holmes uses the telephone extension and disguises his voice as Conover's to get the true name of the person who bought the final bust, the one that must have the pearl in it. Naomi Drake had changed the details of the owner in the shop's ledger and as Naomi makes her exit out the fire escape, she's arrested by Holmes and a waiting policeman.

Conover and The Creeper arrive at the house of the owner of the final bust, Dr. Julien Boncourt, only to find that Holmes has taken his place. Overpowered by Conover, Holmes convinces The Creeper that his beloved Naomi Drake is dead and that Conover will double-cross him. The Creeper kills Conover and turns on Holmes, who shoots him in self defence. Lestrade and some bobbies finally arrive, and Holmes smashes the final bust and recovers the Borgia Pearl.

The films closes with Holmes talking to Watson about the cursed pearl “with the blood of five more victims on it”, and saying that “The struggle will go on…'til the greed and cruelty are burned out of every last one of us. And when that time comes, perhaps even the pearl will be washed clean again”.