Best friends Georgie and Jem aren't just new at school; they're new at being full-time sisters too. Georgie's mum and Jem's dad have finally bought a house together, and they get to share a home at last, just like they always wanted. But being full time sisters is maybe a tiny bit harder than they expected.

At school, there are new friends to make and a new class project to complete. Everyone must write down their deepest secret so that their teacher Miss Eagle can set a giant ball alight and they can all watch their worries disappear.

But the ball of secrets mysteriously disappears and everyone's secrets are revealed. Can Georgie and Jem discover who the secrets thief is and learn how to stick together in their new family?