Science geek Meg is left to look after her little sister for ten days after her free-spirited mum leaves suddenly to follow up yet another of her Big Important Causes. But while Meg may understand how the universe was formed, baby Elsa is a complete mystery to her.

And Mum's disappearance has come at the worst time: Meg is desperate to win a competition to get the chance to visit NASA headquarters, but to do this she has to beat close rival Ed. Can Meg pull off this double life of caring for Elsa and following her own dreams? She'll need a miracle of cosmic proportions …