Turning from historical romance to more traditional roots in science fiction and fantasy, Bradley goes back to the early days of Darkover as the setting for The Heirs of Hammerfell. Those unfamiliar with the history of Darkover are brought up to date in a brief preface. From the time a stray Terran starship landed on the planet, Darkover passed through the Age of Chaos into the Age of the Hundred Kingdoms, a feudal period dominated by the House of Hastur. Hastur is ruled by a hereditary aristocracy called the Comyn, which emerges to consolidate its rule in the Seven Domains. Ultimately, the technologically advanced Terran Empire rediscovers and reestablishes contact with Darkover. Prominent in the Darkover fantasy-scape are the priestesses of Avarra and the warriors of the Sisterhood of the Sword, who preserve a tradition of wise warrior women in the restrictive world of patriarchal Darkover. Also prominent are the matrix technologies which evolve in the Comyn clan to embrace various psi powers, including laran, a telepathic ability to enter other's minds and thoughts, and clingfire, a terrible mental weapon.

The Heirs of Hammerfell is set in the earlier part of Darkover history when the Hastur lords are establishing their hegemony over outlying domains. Among these are the wild and remote Hellers, whose mountains separate the Seven Domains from the Scathfell lands beyond the Comyn Compact. Two of the Heller clans, Hammerfell and Storn, are locked in a blood feud, which appears to take a decisive turn when Storn destroys Hammerfell castle and its Duke Rascard. Erminie, the young Queen of Hammerfell, and Alistair, the elder of her twin sons, find refuge in the bustling, wealthy capital city of Thendara. Alistair's younger twin, Conn, is separated from his mother and brother during the flight and raised in secret by a loyal retainer. Once they are reunited in Thendara, the brothers return to the Hellers to confront Lord Storn. After a raging forest fire and some romantic mix-ups, the clans of Hammerfell and Storn are united through the marriage of Alistair to Lenisa, the grandniece of old Lord Storn.