Felix Spark’s little sister is a fixologist. Astrid can fix cracked cups, broken toys, Felix’s thumb, even Dad’s Harley Davidson when it gets swallowed by a hole in the back lawn. But Astrid can’t fix what’s under the house, threatening to destroy the whole world - that takes a rock band, a didgeridoo, an astrophysicist and a few thousand echidnas.

Get ready for an incredibly close encounter of the third (fourth and fifth) kind....