When Matilda shares her woes with her Grandma Joss, she’s astonished to learn her grandma was once a scientist herself – an astrophysicist, who discovered her very own planet. Trouble is, Grandma Joss was also overlooked – her boss, Professor Smocks, stole her discovery for himself. And he’s about to be presented with a Nobel Prize.

Matilda concocts a plan. They’ll crash the award ceremony and tell everyone the truth! So begins a race against time – and against Matilda’s strict mum and dad! – on a journey through Paris, Hamburg and Stockholm, and on which they encounter a famous film star, a circus, and a wanted diamond thief…