Robert Amiss is in a mess, and he faces the indignity of life on the dole. So when his old friends in the CID ask him for help, he is in no position to refuse. Strange things have been happening at the Knightsbridge School of English. One teacher has met a suspicious death and another has been attacked, apparently the victim of a random mugging. Are the two events connected? Amiss unwillingly agrees to be the CID's mole at the school.
