Vimes, along with family and several members of the Watch, travels to Koom Valley. He believes he is pursuing justice, but an astute troll king named Mr. Shine and a bright young grag named Bashfulsson know that Vimes is carrying the Summoning Dark, the quasi-demonic entity that wreaks vengeance on dwarves who have done evil in the sight of other dwarves. Vimes acquired the Summoning Dark when he touched the cursed door in the city mine, but his own internal watchman proves stronger than it is.