The Callum children spend their Easter Holidays in Norfolk with a family friend, Mrs. Barrable, who is staying on a small yacht called the Teasel, moored near the village of Horning. There they encounter the Coot Club, a gang of local children comprising Tom Dudgeon, twin girls 'Port' and 'Starboard' (Nell and Bess Farland), and three younger boys — Joe, Bill and Pete (the Death and Glories).