In an isolated house on the cliffs of north Cornwall the sibling rivalry between identical twins Max and Ashley Hennessy is coming to a murderous climax. They both know one of them must die, but, trapped in his wheelchair, Ashley knows the odds are now against him and he is in mortal danger - but does DI Fergus believe him? And can he trust Nurse Malahide, who has been employed to protect him? Poor Lalla, the twins' aunt, is torn between the two boys: which of them is the victim and which is the psychopath? Perhaps they have done it once again - pulled off the final 'switch'.
