A lovingly restored old mill goes up in flames, just before its presentation at the Open Jura House Week. In the ruins of the fire lies the dead owner, a former district judge and uncompromising heritage conservationist, who had fought against the demolition craze in the Altmühltal. Commissioner Mike Morgenstern investigates a case that occupies him personally more than he would like: His wife Fiona dreams of having her own Jura house, with a stone slate roof and thick rubble stone walls. But old beams have enemies, and wood-eating beetles are not the most dangerous of them.