Immortality - Skulduggery Pleasant Fan-Fiction

Valkyrie is back in after five years spent living in Meek Ridge, America. But of course, as soon as she gets back, there's a problem. A man named Atramentous Sickle, a powerful Necromancer and Elemental, and a mass serial killer, has broken out of Newgate Prison and is out for Skulduggery. And when Valkyrie thinks it can't get worse, it does. How will Skulduggery fight off Atramentous and how will Valkyrie fix this massive problem that will change the world forever.

This book is meant for after The Dying of The Light.