Lady Constance Keeble, sister of Lord Emsworth of Blandings Castle, has both an imperious manner and a valuable diamond necklace.
The precarious peace of Blandings is shattered when her necklace becomes the object of dark plottings, for within the castle lurk some well connected jewel thieves - among them the Honourable Freddie Threepwood, Lord Emsworth's younger son, who wants the reward money to set up a bookmaking business.
Psmith, the elegant socialist, is also after it for his newly married chum Mike. And on patrol with the impossible task of bringing management to Blandings is the Efficient Baxter, whose strivings for order lead to a memorable encounter with the castle flowerpots.
Will peace ever return to Blandings Castle...?