London, 1905. The city runs on coal and engines, and clear skies are rare. Mary Clarissa Christie is a university student living alone while her mother works abroad, spending quiet days with her friends Angelica Derleth and Charlotte Bronte. A chance encounter pulls her into the city's hidden world: the rumors about Metacreatures hunting at night have turned out to be true. Mary makes a contract with a mysterious figure known only as M and begins hunting them alongside him.