Heir of Sea and Fire is a fantasy novel by Patricia A. McKillip. It is the second book of the Riddle Master Trilogy. The other two books are The Riddle-Master of Hed and Harpist in the Wind. It was published in 1977.
All three books were collected into the volume Riddle-Master: The Complete Trilogy in 1999.
In the second book of the series, the focus shifts from Morgon of Hed to Raederle of An. Raederle, the heir of sea and fire referred to in the title, was promised by her father to the man who won a riddle game with a ghost. In the previous book, this was revealed to be Morgon, but as this book opens, he has been missing for a year; since his power over the land of Hed has just passed to his heir, he is thought dead.
Raederle sets out for Erlenstar Mountain, where Morgon was trying to reach when he died. Along the way, she is assisted by the Morgul of Herun's heir and by Tristan of Hed, Morgon's sister. The first half of the book chronicles their journey north. Along the way, Raederle grows to understand her own significant powers as a descendant of both shapechangers and witches. Her hidden ancestry makes her related to Morgon's enemies. Midway through the book, she discovers that Morgon is alive, while shapechangers and Ghisteslwchlohm, an ancient, evil wizard and traitor from ages past pursue him.
Sensing a powerful, dangerous force in pursuit across her land, Raederle uses her abilities to confound it, thinking she is protecting Morgon; but discovers that the force she thought was Ghisteslwchlohm is Morgon himself, who has stolen much of Ghisteslwchlohm's power during his long captivity, while the helpless man he pursued was Deth, who betrayed him. Confronted with this, and realizing how he appears, Morgon forsakes his revenge and allows Deth to escape.