On New Year's Day 1891, Sherlock Holmes summons the limping street urchin, Wiggins, to Baker Street and decrees he must die at dawn. Wiggins, however, has other plans. To fulfil the dying wish of his mother, Irene Adler, he schemes with his two formidable American aunties to keep two important facts from the great detective: Mrs. Hudson is actually his Aunt Grizelda, and he is both Holmes' child and a girl pretending to be a boy. Through a series of mysterious letters Adler bequeathed to Wiggins, the dark backstory of her parents and all their long-kept family secrets unravel. To flee the mad King of Bohemia trying to claim Wiggins as his heir, Holmes and Wiggins begin their Great Hiatus. From Mycroft to Moriarty, from Dr. John H. Watson to the Baker Street Irregulars, from P. T. Barnum to Jumbo the Elephant, Wiggins learns little is what it seems. Slowly learning to trust each other, Holmes and Wiggins travel from London to Reichenbach Falls to New York City to a small farm in Canada which holds the secrets of their family history. Together, they correct the errors in Watson's tales, bond over Wiggins' disability, drop their masquerades, and deduce a father and daughter future.