Rebecca Mason had been expecting to go on holiday with her parents at the end of her year in the Third at Trebizon School. But a last-minute telegram and a fruitless journey to Bath result in her returning unexpectedly to join her friends, helping with the children's summer camp in the school grounds. And looking after Tommy Carter provides plenty of drama. But when he becomes involved in Mrs Lazarus' excavation for Roman coins in nearby Mulberry Cove, Rebecca and her friends are in for even more than they bargained.