Jack’s grandpa is a lovable old man who, despite his age, still loves adventure. He wears his slippers to the supermarket, serves up Spam à la Custard, and often can’t remember Jack’s name. But Grandpa is also secretly a former Spitfire pilot, and when danger looms at home, he and Jack team up for a daring escape and a wild flight over London. The story is funny, heartfelt, and full of unexpected twists, celebrating the bond between child and grandparent and reminding us that strength and heroism can hide in unlikely places.