The Sleepwalking Vampire (The Decoders)

Twelve-year-old detectives Steve, Matt, and Jenny agree to help their friend Tyrone with a unique problem -his niece thinks she's a vampire. Believing the girl simply has an over-active imagination, the trio spends the night at her home, determined to ease her worried mind. But when the young girl vanishes and a bat turns up in her place, the three friends find themselves facing something they never thought possible -a real vampire.