An apartment in an old building in the lower quarters of Prague with a sign adorned with three frogs. A woman lived there with her two children, twins, about ten years ago. This is what Temma learns from the neighbors. They also tell him about the Czechoslovak secret police and a strange fire. Could the twins be Johann and Anna? Meanwhile, Suk, a young Prague police inspector, falls for a pretty girl he met in a bar. Her name is Anna! When Tenma and Suk meet, a new tragedy is brewing around them!