Laura is baking a cake in class tomorrow. There's only one problem: Mrs Large has run out of flour. They try the shop but it's closed. They try driving to Granny's but the car breaks down. On the way to school next morning they meet Sebastian Smart, who's in Laura's class - and he has a big basket of ingredients! If only Mrs Smart would let her son share some flour. But after baby Lucy creates a messy surprise, they resolve to make one cake, together.