The Jewel of Covent Garden — Wayne Worcester

From the never-before-published journals of Sherlock Holmes's companion and chronicler, Dr. John Watson: a tale of nefarious doings that nearly brought down London's wealthiest woman--and made its most famous sleuth Scotland Yard's most wanted....

Something fishy is afoot when a young boy from the streets appears at 221B Baker Street with a gilded invitation. No one, including Holmes, knows why a poor young commoner would be invited to a spectacular dinner gala with the creme of London society. Even more strangely, someone is impersonating. Holmes--the master of disguise himself--and publishing mysterious messages under his name.

As the famous sleuth investigates these odd occurrences, he finds more amiss than not. And it all has something to do with a jewel worth a hundred fortunes, a ruby said to bestow luck on its owner--the fabled Blood of Punjab....