Death Cloud by Andrew Lane
Fourteen-year-old Sherlock Holmes is horrified when his older brother, Mycroft, tells him that instead of returning home for vacation, he will be staying with his aunt and uncle-who he doesn't even know. His stay there is made even worse by the awful housekeeper, Mrs. Eglantine. Thankfully, Sherlock is able to make friends with a local poor boy, Matty.
When Sherlock finds a dead body in the woods covered in what appears to be boils from the plague, he is determined to find out why the man died. With the help of Matty and Sherlock's tutor, Amyus Crowe, Sherlock investigates the dangerous mystery. Soon, it is clear that the man's death was deliberate, not an illness. Can Sherlock find out who is behind the murder before more are killed?
**Book 1 in Sherlock Holmes: The Legend Begins**
Next book: Rebel Fire
"Sir Arthur Conan Doyle left many clues to Sherlock Holmes's origins in his tales, but it has taken Andrew Lane to do the detective work of ferreting them out and fitting them together into an intelligent, authentice, persuasive, and downright exciting depiction of the English boy who will one day become Mr. Sherlock Holmes of 221B Baker Street, London, the world's first consulting detective . . . It is a profile Conan Doyle would not only recognize, but would agree enthusiastically as being consistent with his own image of the character."
-The Conan Doyle Estate