It's the first day of the holidays, and Blyton starts us off with the description of Roger and Diana's scrumptious breakfast. The Lynton family is in a frenzy of activity to arrange the house for the arrival of two guests-Snubby and Great-Uncle Robert-on the same day. The combination of the idiotic Snubby, lunatic Loony, spiteful Sardine and pompous Uncle Robert seems like a recipe for disaster, but disaster strikes even before they are under the same roof.
Snubby is travelling in the same railway carriage as Great-Uncle Robert, but they have never met, and they don't know they are heading for the same destination. Here is where we get a whiff of the mystery-Great-Uncle Robert sees Snubby reading about spies, and he tells him about his tribulations. We learn that Great-Uncle, who is an antiquarian (someone who studies, collects, or deals in antiquities, and not someone vehemently opposed to aquariums) was living in the Chelie Manor when valuable papers disappeared mysteriously. All doors were locked, all windows were barred, and they stayed that way, but the thief got away with the goods. Snubby thinks that the old man is feeding him a cock-and-bull story, and decides that two can play that game. However, being Snubby, he goes overboard and invents a green-glove-wearing Green Hands Gang who have the secret of the atomic bomb! If this wasn't enough, he says he is being pursued by them and is going to his cousins' place to be safe.