In a world covered by a deadly miasma, humans survive by way of the protection of powerful mages known as Keepers. In the town of Ravenhearth, the Keeper requests a companion from the village every ten years. What happens to them after those ten years, no one knows, for none has ever returned.

Ash is a young orphan who dreams of learning magic. When the newest request for a companion arrives, he volunteers. But when he arrives, he finds a place nothing like the fearful whispers shared around the village. Instead, he slowly grows to be a part of the close-knit family of the Keeper's castle—and falling for Giles, the butler of Ravenhearth, instead of the Keeper he's been sent there to attend.