When young cook Kat Holloway learns that the children of London's Foundling Hospital are mysteriously disappearing, she can't turn a blind eye. East End parish vicar Errol Fielding has his suspicions, but the police brush him off, and Kat - and his childhood acquaintance Daniel McAdam - are his last option. Kat and Daniel are determined to solve the mystery, and Kat engages the help of her scullery maid, Elsie, who reveals she had been a foundling. Their investigation takes them to the less hospitable areas of London, including the very streets where Kat grew up. She soon suspects the answers they seek are much closer to home than any of them realised.