Emily Baines and May Brewer share a room in a retirement home. Emily's previous room-mate, Bella, died not long ago. Iron-willed but forgetful, Emily is certain that Bella was murdered by one of the carers, and she has evidence to prove it. When her evidence disappears and Bella's sapphire ring is found among her possessions Emily cannot remember enough about her own past actions to stop the finger of suspicion pointing at her. It is not until May is attacked that the mystery is solved.