When unexpected debris and creatures from outer space crash onto their peaceful planet, the Clangers explore these strange arrivals with curiosity and wonder. An astronaut arrives in his shiny spaceship on the Clanger's peaceful planet. Oblivious to the charming inhabitants of the planet he has visited, he spends his time gathering all sorts of rocks in his basket.

Thinking rocks a curious thing to collect, the Clangers secretly replace the boring rocks with their delicious blue string puddling. There are much more interesting treasures to collect than rocks.

The astronaut is quite shocked to find his basket of rocks replaced with pudding. Startled at the presence of the Clangers, he tangles, trips, and troubles and puts himself into all sorts of trouble. The Clangers along with their friends kindly assist him with their gentle demeanour. Once the astronaut is well, he flees to his rocket quickly departing. The Clangers wave him goodbye and wish him well on his journey hoping to see the astronaut again.