Martha is lost. She's been lost since she was a baby, abandoned in a suitcase on the train from Paris. Ever since, she's waited in station lost property for someone to claim her. It's been sixteen years, but she's still hopeful. In the meantime, there are mysteries to solve: secret tunnels under the station, a suitcase that may have belonged to the Beatles, the roman soldier who appears at the same time every day with his packed lunch. Not to mention the stuffed monkey that someone keeps misplacing. But there is one mystery Martha cannot solve. And now the authorities have found out about the girl in lost property. Time is running out - if Martha can't discover who she really is, she will lose everything...