Vampirates: Black Heart by Justin Somper
There's a new ship of vampirates roaming the seas, leaving a trail of fear and devastation in its wake. When a high-profile pirate is slain, the Pirate Federation takes decisive action and begins training up a ship of dedicated vampire hunters. Amongst the dynamic crew is young pirate prodigy Connor Tempest. Meanwhile, Connor's twin sister Grace enjoys a bittersweet reunion with their mother, Sally, who has some important and shocking news for her daughter. As Grace uncovers the truth about her family's past, she realises that she and Connor face a daunting and uncertain future.