Drawing from Welsh, Celtic, Christian, and Roman mythology, the story opens on the island of Erin — western edge of the Holy Empire. A rogue priest named Drwc kidnaps the precognitive Gael priestess Rhiannon, intending to sacrifice her to resurrect the Demon King Arawn and win his favor. The Gael burn their village and march to get her back. When Arawn is resurrected mid-ritual, he kills Drwc, frees Rhiannon, and declares no interest in conquest or destruction. Rhiannon falls for him on the spot, publicly declares him her husband, and makes him chieftain of the Gael tribe. The story then shifts to Arawn as protagonist, following the tribe's exodus from Erin to the neighboring isle of Albion as they try to outrun the reach of the Holy Empire.