TKKG - The Secret of the Mysterious Mind Machine(2006)

At first, friendgroup TKKG have no idea that something is amiss when “Jugend forscht” winner Kevin behaves strangely during the presentation of his “Mind Machine” - they blame his nervousness and his unexpected termination of the speech on relationship stress with his girlfriend Nadine. But when Nadine disappears without a trace shortly afterwards, like three other children before her, the amateur detectives know that they have to help the police with their investigation.