Shadowghast by Taylor Thomas

A mysterious stage magician has set up in the theatre at the end of the pier, with an act so hypnotic and strange that Herbie Lemon and his friend Violet Parma suspect dark forces are at work. Meanwhile, folk are disappearing from Eerie-on-Sea, and no one knows why. There is an Eerie legend that goes back to the dawn of time, about a creature made of darkness that devours the shadows of the living. But could the Shadowghast really have returned?