Conan Doyle for the defence: a sensational murder, the quest for justice and the world's greatest detective writer

Just before Christmas 1908, Marion Gilchrist, a wealthy 82-year-old spinster, was found bludgeoned to death in her Glasgow home.

A valuable diamond brooch was missing, and police soon fastened on a suspect - Oscar Slater, a Jewish immigrant who was rumoured to have a disreputable character.

Slater had an alibi, but was nonetheless convicted and sentenced to death, later commuted to life imprisonment in the notorious Peterhead Prison.

Seventeen years later, a convict called William Gordon was released from Peterhead.

Concealed in a false tooth was a message, addressed to the only man Slater thought could help him - Arthur Conan Doyle.

Always a champion of the downtrodden, Conan Doyle turned his formidable talents to freeing Slater, deploying a forensic mind worthy of Sherlock Holmes.