Huw always pops in to see his nan on the way home from school – she bakes him cakes and never fusses about his homework. So it’s a great shock when, one day, Nan forgets his name, and calls him Johnny – the long-unmentionable name of her late brother. As Nan slowly slips into the grip of dementia, Huw and his friends go on a quest to learn more about Johnny and what happened to him.