Four objects of various shapes and colours arrive on the Clangers’ planet. They disappear underground as a fifth one arrives. The objects can change shape to disguise themselves and hide from the Clangers, so they go unnoticed. But the fifth object is discovered upon its arrival, and Granny realises this is a group of 'hide and seekers', travelling the universe on an intergalactic game of hide and seek. Intrigued, the Clangers join in the seeker’s successful quest to find the four hiders.