In 1915, long since retired from his observations of criminal humanity, Sherlock Holmes is engaged in a reclusive study of honeybee behavior on the Sussex Downs. Never did he think to meet an intellect to match his own– until his acquaintance with Miss Mary Russell, a very modern fifteen-year-old whose mental acuity is equaled only by her audacity, tenacity, and penchant for trousers and cloth caps.

Under Holmes’s tutelage, Russell hones her talent for deduction, disguises, and danger: in the chilling case of a landowner’s mysterious fever and in a kidnapping in the wilds of Wales. But her ultimate challenge is yet to come. Soon the two sleuths are on the trail of a murderer whose machinations scatter meaningless clues…but whose objective is quite unequivocal: to end Russell and Holmes’s partnership–and their lives.