The Sign of the Four

"I really liked the map, and the secret signs. Toby the tracker dog is very clever to help Sherlock Holmes." Mehtan, 10
'I find myself in a very strange and mysterious situation.'
When Miss Mary Morstan is invited to meet a secretive stranger, she asks Sherlock Holmes and Dr Watson to help her.
Captain Morstan has disappeared from his hotel without a trace. Should Miss Morstan dare to hope that her father is still alive?
What horrible scene awaits the famous detective and his friend when they break down the door to Bartholomew Sholto's attic room?
Who is the man with the wooden leg, and why is he so full of bitterness and hatred? Will Toby, the cleverest tracker dog in London, help Holmes and Watson solve one of their most difficult cases?