The Adventure of Vanaprastha by Hugh Ashton

Sherlock Holmes is called to investigate the death of Colonel Cardew, who has been savagely tortured to death in a locked room.
The mystery seems insoluble, but Sherlock Holmes discovers the solution, which has its roots thousands of miles away and many years previously.
A Sherlock Holmes adventure from the writer who has been described as "the reincarnation of Sir Arthur Conan Doyle".