Trollslayer, a novel written by William King, is the first in a series of twelve books following the adventures of Gotrek and Felix, in the Warhammer Fantasy universe.

It shows the background for many important things in Felix's reminiscing in other stories, such as his first encounter with Chaos and his first great love, not to mention where he got his magical sword.

They reach the Standing Stones Inn, and are able to make their way through the barred door to learn of how on Geheimnisnacht a coven who are based in the Darkstone Ring steal children and other people for sacrifices.

They finally attack and destroy the coven as they intended to sacrifice a stolen baby, and in the aftermath they discover that Gunter and his wife were both cultists, and so are both dead.

The story begins with Felix in a tavern protecting a girl from the attentions of three huge trappers: Hef, Kell, and Lars.

After traveling through the Grey Mountains, and reaching the Border Lands, Felix falls deeply in love with Kirsten, and she likewise.

The men drive off the Undead, and they set off to find a ruined fort, which Gotrek helps repair, hinting at his pre-slayer background as an engineer.

Finally, the fort is attacked by Wolf Riders, led by a Goblin Shaman, and during the first siege, Gottfried, the leader of the von Diehls, is struck by an arrow and is carried off by his son, Deiter; his nephew, Manfred; Frau Winter, a sorceress; and Kirsten, Frau Winter's assistant, to be healed.

After a day of no word from them, and with the second siege starting, Felix goes off to investigate, leaving Gotrek and the remaining men to fight off the horde ready to break through the gates.

He then comes across Dieter, whose head was bashed in, and enters Gottfired's room to see him stabbed to death in his bed with Manfred sitting there wiping off his blade.

The story continues immediately after 'Wolf Riders', with Felix and Gotrek travelling towards Karak Eight Peaks in search of treasure.

The pair intervene and save the three survivors: Aldred Keppler, a zealous fanatic from the Templars of the Fiery Heart, Johann Zauberlich, a sorcerer, and Jules Gascoigne, a Bretonnian scout, are also journeying to Karak Eight Peaks on a quest.

Gotrek realizes they are in a Dwarven tomb, and that the troll's presence is the reason why the ghosts are stalking the ruins of Karak Eight Peaks.

As Gotrek and Felix consign themselves to dying in battle, the ghosts of the tomb form up in a spectral army and attack the goblins, killing them with ease and causing the survivors to flee.

To make matters worse, in a battle with mutants on the road, Gotrek was struck on the head with a slingstone and is suffering amnesia, no longer remembering who he is, nor who Felix is, or his quest to find a heroic death.

Narrowly avoiding the Slaaneshi thugs and a roving band of mutants, Felix gathers the ingredients and brings them to Kryptmann.

Kruger, now a megalomaniac egotist, arrogantly explains that he plans to use the knowledge in the texts to create an army of mutants with which to conquer the Empire.

However, the pair break free of their captivity and fight back: when Kruger sends Oleg, the most powerful of his mutated soldiers, to kill them, Gotrek strangles the mutant with the chains he was bound with.

In a burst of uncharacteristic fury, Felix seizes Kruger by the throat and throws him to his death from the castle battlements, an act that meets with Gotrek's approval.

Felix is bound in chains next to another captive, Magdalena, a beautiful young woman the cult have captured for their dark purposes...

They capture Magdalena, and although Felix considers her an innocent in the affair, Gotrek believes that as a shapeshifter she is tainted by Chaos and kills her.

In his introduction to the 2013 edition of Trollslayer, William King revealed that he wrote Geheimnisnacht as a one-off story, in 1988, in which Gotrek was meant to die at the end, but later revised it based on his liking for the characters.

However, Games Workshop Books closed unexpectedly, and the publication of the novel was delayed until 1999, when it also included The Mutant Master and Ulric's Children, which had previously been published in Inferno!