Arthur (Art) Mumby and his irritating sister Myrtle live with their father in the huge and rambling house, Larklight, travelling through space on a remote orbit far beyond the Moon. One ordinary sort of morning they receive a correspondence informing them that a gentleman is on his way to visit, a Mr Webster. Visitors to Larklight are rare if not unique, and a frenzy of preparation ensues. But it is entirely the wrong sort of preparation, as they...

When the festive season arrives at Larklight, so does some unsettling news. A sinister-looking cloud is fast approaching the outskirts of the Known Universe. The closest planet, Georgium Sidus, has but two human inhabitants: the missionary Revd Cruet and his daughter Charity. Their most recent communication read: 'Great danger . . . imperative that -'

And so, aboard a naval gunship, Art, Myrtle and family bravely go where only one man

...

At the edge of space, a mysterious cloud appears. The last transmission from a remote outpost near the cloud warns of grave danger. Now Art, Myrtle, and the rest of the family launch an investigation-and what they find is so horribly, terribly monstrous that not even a billion mothballs will keep it at bay!