The book opens with the mysterious arrival of a baby in Edinburgh, 1773. The scene shifts to the city fifteen years earlier.
The Doctor and Martha are confronted by the walking dead, first a solitary figure which attacks a stagecoach containing Benjamin Franklin, then by an army of the creatures rising from the putrid waters of the Nor' Loch. The British soldiers under Captain McAllister who have arrested the Doctor find themselves following his lead. Part of this is the soldier's desire to save innocent civilians endangered by the creatures.
Meanwhile, at the Surgeon's Hall, Martha has met a couple of physicians, Alexander Monro, senior and junior, who apparently brought the first corpse back to life. They lock her in a small room with dozens of hands, disembodied but disturbingly active.
The Doctor deduces the presence of a modular alien and discovers its sinister intentions.
Benjamin Franklin reappears in the final chapter, set in 1771, meeting Alexander Monro, who reclaims the hand he gave Franklin years before, the last one on Earth.
