Amy finally discovers the full scale of the conspiracy, and she must decide if she is prepared to risk everything to find those responsible.

Sherlock faces perhaps the most chilling enemy of his long career: the powerful and seemingly unassailable Culverton Smith – a man with a very dark secret indeed.

Sherlock faces perhaps the most chilling enemy of his long career: the powerful and seemingly unassailable Culverton Smith – a man with a very dark secret indeed.