Karin Lossow meets the mysterious Mandy, who is apparently stalking her colleague Martin Rabe and his parents. Shortly afterwards, Martin's fiancée Antonia is found dead. While Rainer Witt investigates Antonia's company, an innovative start-up for water desalination, Karin Lossow uncovers Mandy's harrowing connection to the Rabe family – a story that goes back to the GDR and the fall of the Berlin Wall in 1989.