Conor and Grace are twins, recently orphaned after their widowed father's death. Rather than being adopted by the town's busy-bodies, they decide to set sail in their father's last possession, his sailing boat. But a vicious storm sees their boat capsize and the twins are separated. Two mysterious ships sail to their rescue - each picking up one twin before disappearing into the mist. Conor wakes to find himself on a pirate ship and is soon being trained up with a cutlass. Meanwhile Grace finds herself locked in a darkened room, as the vampirates wait for night to fall and their feasting to begin. . . Determined to find each other, yet intrigued by their new shipmates, the twins are about to embark on the biggest adventure of their lives. . .