Rodolpho Aranda, head of an Argentinian chemical company, is found murdered in a Berlin bookshop: An elderly librarian named Valerie Steinfeld poisoned him with cyanide and then took her own life. As the LKA was unable to establish any connection between the victim and the perpetrator, the motive for the crime remains unclear. When Aranda's son Manuel arrives to transfer his father's body to Argentina, the case is officially closed. Instead of an explanation, the young doctor only receives a sealed zinc coffin - the search for the truth is left to him.