Kaye Whiting went to buy a birthday present and didn't come back. She isn't dead, or physically injured, but she is alone and very scared. Fifty miles away in Cambridge town centre a deeply disturbed young woman is standing by a payphone. She knows she often feels compelled to do harmful things, and is now driven by the desire to make a call. DC Gary Goodhew listens to her anonymous voice saying "Kaye isn't the first and won't be the last". He knows it is their only clue.