The mentally handicapped Andreas Brose, better known in Schwanitz as "The Andy Next Door", is a hunk of a man and gifted with his hands. He repairs Hauke's broken boat engine and helps Hannah renovate her new house. Andy's mind, heart and instincts are more like a child's though. When Andy finds his beloved foster father Cem Brose dead, he is suspected of murder because of a witness statement. Hauke and Hannah determine that the old man was once a treasure hunter. Could the murder be related to a stolen diamond that the adventurer owned? While the investigation is ongoing, there is a second fatality and then Andy suddenly disappeared.