Teenagers Holly Ledford and Kelsie Harland have been best friends since pre-school, they and their group of friends don't know about the magical links their village of Marlbury has - or the implications this will have for their futures - but the adults do.
Pragmatic Holly is unknowingly on a predestined path to continue Avalon's effort to maintain a pact between humans and the natural world - unwittingly, she helps a tree transform into a man, Crae. Just as Avalon has planned, Holly falls in love with Crae.
But there is a problem, many miles North on a Scottish mountain, the Goddess of Winter and her son discover Avalon's plans, and are incensed that they cannot bring the Winter southwards. Desperate to stop the pact between humans and the natural world, the Goddess tries to attack Holly and Crae, she is in vain, so instead, she takes Kelsie hostage - believing she is weak and powerless.
But not even the Goddess is prepared for what happens next.
In the epic conclusion to the Devil's Deal series, Freya has one final chance to discover the full potential of her own power, and to use it to restore balance in the universe - once and for all. After the destruction caused by Roisin, Ferya and Torix come to terms with their losses and mistakes... And prepare for a final battle that will change everything.