Exploring their neighbourhood, Pim and Klara come across a curious stranger-a lost deep-sea diver who seems to need their help. Can the siblings work together and figure out where he belongs?

With Klara enthralled by an intriguing neighbour and Lucy starting a new job, Pim needs someone to play with. He builds a dinosaur friend out of junk, stunned when it comes to life. But their fun quickly gets out of hand.