Tallinn, 1419. What links the Keeper of the Tower, a prostitute and a Flemish painter to a haunted house on Rataskaevu Street? All three claim to have seen a ghost near the house, and each is found dead soon afterwards.

Melchior Wakenstede, apothecary and assistant bailiff, is charged with unearthing the truth. With a cultivated sense for justice, Melchior investigates the deaths and attempts to find out whether, as the denizens of medieval Tallinn believe, ghosts can reap their revenge upon the living.

When a powerful merchant dies, Melchior perceives a corporeal connection between this and the other deaths. As Melchior becomes embroiled in the conflicts and rivalries between religious orders, merchant guilds and Teutonic Knights, all vying with one another for control of the town, what he discovers is more incredible and more terrible than any ghost.