Sherlock Holmes assists a popular mystery writer whose plots seem to be coming to life.

May 1898. A new client arrives at Baker Street - Abigail Moone, a wealthy, independent writer of successful mystery stories under a male pseudonym. She presents an unusual problem. Abigail claims that she devised a man's death that was reported in that morning's newspaper: that is, she planned his murder as an event to be included in one of her mystery stories. Following real people and imagining how she might murder them and get away with it is how Abigail comes up with her plots, but this victim has actually died, apparently of the poison method she meticulously planned in her notebook. Someone is trying to frame Abigail for his death, but with the evidence stacking up against her, she turns to Holmes to prove her innocence.