The narrator of The Beekeeper's Apprentice, Mary Russell, is a brilliant but unhappy young woman, recently orphaned and now heir to a sizeable estate, who literally stumbles over a rather famous retired detective in the middle of the Sussex Downs.

When she and Sherlock Holmes meet, she is 15 and he is 54, but the two form an instantaneous friendship which soon becomes a partnership as he begins to teach her the art of detecting. They pursue a succession of cases together, but what began as a pleasant diversion swiftly turns into a deadly game of chess with a mysterious, ruthless enemy from Holmes' past.