From out of the past, the year 1885 finds Doctor John H. Watson down on his luck. His prospects look bleak, until a chance encounter leads him to a meeting with another literary-minded young physician named Arthur Conan Doyle. Together, they hatch a plan for a series of works based on the adventures of Watson's roommate, the consulting detective, Mr. Sherlock Holmes.

Then, a very attractive young lady, Mary Morstan, arrives at 221 B Baker Street, seeking help. Soon Holmes and Watson are drawn into the dark world of the Sholto brothers, a web of blackmail, and murder. Even with the assistance of a rising playwright named Oscar Wilde, Holmes finds himself taxed to the limit of his powers, when his own darkest secrets are exposed. What truths lie beneath the surface of the Picture of Innocence?