1883. Thaniel Steepleton returns home to his tiny London apartment to find a gold pocket watch on his pillow. Six months later, the mysterious timepiece saves his life, drawing him away from a blast that destroys Scotland Yard. At last, he goes in search of its maker, Keita Mori, a kind, lonely immigrant from Japan. Although Mori seems harmless, a chain of unexplainable events soon suggests he must be hiding something. When Grace Carrow, an Oxford physicist, unwittingly interferes, Thaniel is torn between opposing loyalties.