And Darkness Rained Upon Them

The wonderful Derrek Landy created the Skulduggery Pleasant series and all rights of the characters go to him! (Apart from Raven, and all the other characters he didn't make up, lol)

Valkyrie Cain and Skulduggery Pleasant are called out to a mission in London. Valkyrie and Skulduggery discover shocking secrets and are faced with one of their greatest enemies yet. A new ally falls into their lives with an exuberant entrance, her name is Raven, and soon the allies will have to make their final stand and make difficult choices.
This could either bring them together or tear them apart.