Midnight (Skulduggery Pleasant Book 11), Derek Landy

Skulduggery Pleasant is dead. Valkyrie Cain is cool. Omen Darkly is neither.

For years, Valkyrie Cain has struggled to keep her loved ones safe from harm, plunging into battle – time and time again – by Skulduggery Pleasant’s side, and always emerging triumphant. But now the very thing that Valkyrie fights for is in danger, as a ruthless killer snatches her little sister in order to lure Valkyrie into a final confrontation. With Skulduggery racing to catch up and young sorcerer Omen scrambling along behind, Valkyrie only has twelve hours to find Alice before it’s too late.

The clock is ticking…