Detective Chief Inspectors Frank Elling and Lona Mendt are critically injured during a witness protection mission. The witness, twelve-year-old Sarah, escapes the brutal attack but has disappeared. Special investigators Hagen Dudek and Maya Kaminski take over the case and face a challenging investigation. All files and records related to Lona and Elling's previous mission have mysteriously been deleted. What happened? (Source: ARD) (thetvdb.com)