A portion of the tail of a prehistoric reptile is discovered in Denmark. It regenerates into the entire reptile, which proceeds to destroy buildings and property and generally make a nuisance of itself. It can fly, swim, and walk, and has impenetrable scales, which makes it difficult to kill.
Crime writer Rodian moves into a hotel which used to be the hideout for the thief Mathisen and his gang. However, when Rodian has gone to bed and fallen asleep, Mathisen reads the writer's manuscripts and copies the fictional crimes. This gets Rodian in trouble...
