In the 1980s, schoolboy Jack (Kit Connor) loves hearing his Grandpa's (Sir Tom Courtenay's) tales of his time as a Battle of Britain Spitfire pilot, but with the on-set of Alzheimer's disease, Jack's parents put the old man into a retirement home run by the sadistic Miss Dandy (Jennifer Saunders). When the family gets to visit Grandpa, Jack is shocked at his treatment, also discovering Miss Dandy's plan to swindle the residents. So, helped by his sister and her boyfriend, Jack sets out to free Grandpa, who insists on bringing the other residents with him.