The nice new girl in town, step by irrevocable step, becomes involved in a secret society of older boys that ""began innocently enough,"" but grows into a group that deals in terror, danger and illegality. ""Nasty things breed under stones,"" warns Tom, best friend of ""Goldmaster"" Jeremy and defender of Anna when Jeremy's sister Lindy, who's ""bossy and sly and sharp as a monkey puzzle tree,"" brings her into the group. But Tom, whose compunctions have kept the Som (Society of Masks) in balance, moves away. Weaker, vain, and not very bright, Jeremy presides as the Som adds vicious members who delight in terrorizing the younger ""companions."" As Tom predicted, Anna's loyalty finally gets her into trouble: she defends one of the companions when he is actually performing the ""task"" of accepting blame in school for one of the ""lord's"" misdemeanors, and is brought to trial. Tom turns up in time to defend her against Jeremy's drunken, mismanaged justice, but his efforts are inconclusive. It's Lindy who--in an act that the Som would construe as betrayal--invokes the rationality of the adult world in the form of Harry, her hated but sensible stepfather. Like her compatriot Gillian Cross, Alcock is a master of suspense tales that explore complex moral issues through the actions of well-developed characters in unusual situations. From the first gripping page till the final scene, when Lindy tells Anna that ""Harry says there's a time to break promises and a time to keep them,"" a thoughtful, enthralling, perfectly structured novel.