When a series of inexplicable deaths by hydrogen sulphide poisoning occurs, a university geochemistry professor Shusuke Aoe (Sho Sakurai) is engaged to consult on the cases. During his course of investigation, he meets a strange girl Madoka Uhara (Suzu Hirose) with extraordinary abilities, who is searching for a missing friend. Calling herself "Laplace's Witch", she will bring new clues to the table that will change Aoe's beliefs forever...