The Decagon House Murders is a 1987 Japanese mystery novel, the debut work of author Yukito Ayatsuji. Borrowing its basic plot structure from Agatha Christie's And Then There Were None, it tells the story of a group of seven university students who travel to a deserted island that was the scene of a grisly mass murder six months earlier, where events soon turn ominous. The Decagon House Murders belongs to the honkaku subgenre of mystery fiction.