Edinburgh, 1920. Three children are missing, abducted from the poorhouses of the city.

When a body is found near the town of Liberton, Dr Thomas Stevenson, still suffering from the trauma of the First World War, finds himself drawn into the police investigation. But suspicion falls on the woman with the mysterious past who lives with Thomas. Could she be guilty of the brutal murder?

With time running out and lives at stake, Thomas must prove her innocence, but to do that he has to find the real killer and unlock the truth about her secret past. A past that casts a long, dark shadow.