Mina can heal any wound, but every life she saves must be paid for with another.

When her forbidden magic is exposed after she's forced to drain dying soldiers to save King Uther Pendragon, Mina becomes a valuable commodity, with nobles and generals vying to buy her power. Desperate to escape a future built on sanctioned murder, she turns to the one man clever enough to outwit them all: Merlin.

Merlin offers Mina a bargain that could save her from slavery, but the risks are great. If she smuggles Uther's infant son, Prince Arthur, to safety in the far north, Merlin will guarantee her a new life, anonymous, protected, and free. Assigned to guard her is Vallen, a captured elvish spy bound by magic to protect Mina and the child in exchange for his freedom. As one of the fair folk-ancient enemies of humankind-Vallen resents both Mina and the mission. But as they cross a nation scarred by war, resentment gives way to trust, and trust to a love that could doom them both.

Their fragile alliance is tested when they uncover a genocidal campaign aimed at Vallen's homeland. A rogue general from Uther's army plans to eradicate the elven kingdoms, and Vallen must choose between protecting Mina and warning his people. When Mina is attacked at her supposed place of refuge and Vallen's brutal defense destroys any chance of the quiet life she was promised, Mina follows him into exile to Lurándileth, the hidden elven realm. There, she discovers the truth of her birth: she is the lost daughter of an elven woman and a human king, giving her a claim powerful enough to forge an alliance between enemies divided by centuries of prejudice. To stop the coming slaughter, Mina must convince her newly-found father to ally with his ancient enemies, knowing that failure will cost her both her people and the man she loves.