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. The Watchmaker of Filigree Street is a sweeping, atmospheric narrative that takes the reader on an unexpected journey through Victorian London, Japan as its civil war crumbles long-standing traditions, and beyond. Blending historical events with dazzling flights of fancy, it opens doors to a strange and magical past.

In 1859, ex–East India Company smuggler Merrick Tremayne is trapped at home in Cornwall with an injury that almost cost him his leg. When the India Office recruits him for an expedition to fetch quinine—essential for the treatment of malaria—from deep within Peru, he knows it's a terrible idea; nearly every able-bodied expeditionary who's made the attempt has died, and he can barely walk. But Merrick is eager to escape the strange events plaguing his family's crumbling estate, so he sets off, against his better judgment, for the edge of the Amazon. There he meets Raphael, a priest around whom the villagers spin unsettling stories of impossible disappearances, cursed woods, and living stone. Merrick must separate truth from fairy tale, and gradually he realizes that Raphael is the key to a legacy left by generations of Tremayne explorers before him, one which will prove more valuable than quinine, and far more dangerous.

1888. Five years after they met in The Watchmaker of Filigree Street, Thaniel Steepleton, an unassuming translator, and Keita Mori, the watchmaker who remembers the future, are traveling to Japan. Thaniel has received an unexpected posting to the British legation in Tokyo, and Mori has business that is taking him to Yokohama. Thaniel's brief is odd: the legation staff have been seeing ghosts, and Thaniel's first task is to find out what's really going on. But while staying with Mori, he starts to experience ghostly happenings himself. For reasons Mori won't—or can't—share, he is frightened. Then he vanishes. Meanwhile, something strange is happening in a frozen labor camp in Northern Japan. Takiko Pepperharrow, an old friend of Mori's, must investigate. As the weather turns bizarrely electrical and ghosts haunt the country from Tokyo to Aokigahara forest, Thaniel grows convinced that it all has something to do with Mori's disappearance—and that Mori may be in serious danger.