Sherlock Holmes and Dr. John Watson have been hired by theater actor George Reynolds to find out why the audience who comes to see him perform onstage every night are the same people--only wearing different disguises each time. Is something sinister going on and, if so, what?
Meanwhile, Holmes's archenemy, Professor James Moriarty, is having problems of his own. Implicated in a rival gang leader's murder, Moriarty and his second, Moran, must go on the run from the police as they try to find out who's behind the frame-up.
But their investigation puts them in the way of Holmes and Watson and it's not long before all four realize they're being targeted by the same person. With million of lives on the line, Holmes and Moriarty must form an uneasy alliance in order to unmask the true villain.

For fans of Anthony Horowitz's The House of Silk and Moriarty, this is the first Sherlock Holmes book endorsed by the Conan Doyle Estate in over a decade.