After losing her family in a tragic motor accident in California, fifteen-year-old Mary Russell goes to live with her aunt in Sussex, England. Wandering the Sussex Downs in April 1915, she literally runs across fifty-four-year-old Sherlock Holmes, who has retired from his London practice and keeps bees. The two quickly become fast friends, Russell finding in Holmes a kindred spirit and steadfast teacher and Holmes finding in Russell a quick mind and a worthy apprentice in the art of detecting. By the time Russell enters Oxford University in the autumn of 1917, she is well-versed in Holmes's methods of disguise, tracking, and deduction.