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

Overview:

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.