Wyrm Lord by Simon Kewin

Lost in the land of nightmares…

Cait Weerd has reached Angere in the company of Ran, Nox and the dead witch-girl she carries within her. Now all she has to do is cross the land of the undain without being captured, steal the Grimoire from the Witch King himself, and then, somehow, make it across the famously uncrossable river An.

Oh, and it would be quite nice if she could rescue Danny, too.

Meanwhile, in our world, Fer and her companions must find Johnny’s lost guitar and use it to reach the safety of Andar. But Genera and the undain are closing in, and not everyone will survive the battle.