In the Lovecraft Room of "Usher", his great country house, aging horror star Romney Marsh has gathered together a group of theatre people, ostensibly for a read through of a new play. When the last of his guests has arrived, however, Romney instructs the gatehouse keeper to let loose the guard dogs in the grounds. With a moat full of piranha fish, Romney is confident that his weekend guests are caught like rats in a trap. It seems that someone has been sending him newspaper cuttings about the suicide thirty years ago of Mabel Monk, an actress with whom Romney had an affair, and he intends to find out who is responsible. But before he can, Tanya, one of the actresses, is found with her throat cut, and shortly afterwards Romney himself dies, poisoned by one of his own chocolates. Marooned in the house, with thick fog swirling outside, the other guests soon realise that the murderer must have some connection with the deceased Mabel Monk, and as the action progresses, the finger of suspicion points at each of them in turn, until the final truth is revealed, with fatal consequences.
For Tom and Isobel Goss with affection.