Once a jewel thief always a jewel thief? Yes and no. Yes if you consider the fact that Michael Lanyard also known as the Lone Wolf once retired from the "trade" but relapses back into his old habits when he is tempted by the emerald pendant of beautiful socialite Marcia Stewart. The trouble (?) is that he falls for the belle and he soon gets more interested in getting the girl than the jewels that adorn her. What he wants now is to return the pendant but a rival gang interfere and force him to take part in a big-time caper.

The Good Comrades are a collection of varied gentlemen who crave one thing - solitude. They reside at Drearcliff House, ancestral home of their eldest member. All seems serene and convivial until one by one the members begin to perish in the most grisly of manners. Foul play is suspected by the Good Comrades' insurance agent, who turns to Sherlock Holmes and Dr. John Watson for guidance.

The famous Borgia Pearl, a valuable gem with a history of bringing murder and misfortune to its owner since the days of the Borgias, is brought to London, thanks in part to Sherlock Holmes. But before long the jewel is stolen, due to an error on Holmes' part, and shortly thereafter, a series of horrible murders begin, the murderer leaving his victims with their spines snapped and surrounded by a mass of smashed china.

In World War II, a British secret agent carrying a vitally important document is kidnapped en route to Washington. The British government calls on Sherlock Holmes to recover it.

After the King of Rovenia has been assassinated, Holmes and Watson are engaged to escort his son to Europe via Algiers, aboard a transatlantic ocean liner which also carries a number of suspicious persons, any of whom may be involved in a plot to also assassinate him.

During WWII several murders occur at a convalescent home where Dr. Watson has volunteered his services. He summons Holmes for help and the master detective proceeds to solve the crime from a long list of suspects including the owners of the home, the staff and the patients recovering there.

Sherlock Holmes investigates when young women around London turn up murdered, each with a finger severed. Scotland Yard suspects a madman, but Holmes believes the killings to be part of a diabolical plot.

Holmes and Watson board a passenger train bound from London to Edinburgh, to guard the Star of Rhodesia, an enormous diamond worth a fortune belonging to an elderly woman of wealth; but within the first hour of the trip, the woman's son is murdered and the diamond stolen and any of the passengers in their car could be the killer thief.

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.