Skulduggery Pleasant (Band 11) - Mitternacht

You can't kill a dead man! Valkyrie could have really found a more suitable babysitter than Omen Darkly. He was only supposed to watch over Valkyrie's little sister for a few hours. He was told not to let anyone in and to avoid answering the phone as much as possible. But when Valkyrie and Skulduggery come home, Alison is missing. Cadaverus Gant, Valkyrie's old enemy, has kidnapped her and plans to kill her exactly at midnight. Of course, Valkyrie will do everything she can to find Alison. But she only has nine hours. Nine hours until midnight!

The cult series continues. Because a little thing like the grand finale of his series about the magical skeleton detective couldn't stop bestselling author Derek Landy from coming up with more stories about Skulduggery Pleasant.