The new book from bestselling children's author Gwyneth Rees Sometimes superpowers aren’t so super . . . Emma and her mischievous little sister Saffie like having superpowers – it’s fun making your dolls come to life, teaching Dad’s shoes to dance and playing frisbee with the garden gnomes. But it isn’t always easy keeping their gift a secret – and when Saffie starts to use her power in the naughtiest of ways, Emma has to think fast to save the day! Being a big sister has never been so heroic!

Saffie isn't your average naughty little sister—she's got superpowers! Emma and Saffie are going to stay with their grandparents for the summer to learn how to use their superpowers. Grandma has powers too, but Grandpa doesn't, and he definitely doesn't like the gnomes doing the gardening, or the washing-up doing itself—he'd rather play with his model airplanes. As the summer passes, the girls are having lots of fun—Emma brings a whole doll's house to life (and even learns to bake tiny cakes in the kitchen), but all Saffie wants is to cheer up Grandpa—so she decides to throw him the best party ever. What could possibly go wrong?