Fish (Felicity Imogen Stanley-Holme) and her big sister Roberta have inherited the Fairholme Castle, Roberta being the new Countess, since their father, the Heir, and his wife died in a motor smash when they were little. So, Roberta and Fish go to live in the castle.
Roberta's friend (who she is in love with), Leutenant Jim Hammond, who Roberta met in the WRNS, thinks that she won't need him anymore (he being in love with her, too). Fish befriends Mr Land's (a famous author) guardian, a boy from Singapore called John, who falls in love with her. Though, their happiness (which on Roberta's part is limited because Jim is not there) is not to last for very long. Mrs Redly Boscombe, and her daughter Primrose, recommend a maid of theirs, Hicks, secretly to listen in and report back to them. Hicks overhears Fish telling John that he might be the Heir after all, not Roberta, because his grandfather, George, was the third son of the seventh Earl of Fairholme. Roberta and Fish's grandfather was the fourth. John's father, the third son of George, (also called George) went missing in Singapore, and nobody could trace him until Mr Land, John's guardian, got the lawyers working. The Redly Boscombes spread the rumour around that Roberta is not the real Countess, but an imposter. Jim comes back on the scene, and Fish meets him and keeps in touch with him while he stays in an inn (he doesn't want Roberta to see him). Meanwhile, John thinks Mr Land has finally traced his father, and it sounds like he is the Heir, because Mr Land was "awfully bucked". John doeesn't want to be the tenth Earl at all, for he doesn't want to replace Roberta and it's not the kind of life for him. So he runs away to Wheatley, outside Oxford, to earn a bit of cash before going bak to Singapore. At the ball which happened after the fete (which was on a week after they arrived at Fairholme), Jim proposes, and Mr Land comes, and Fish at first thinks he has come to ruin Roberta's joy, to depose her. But, he has only come to ask her if she had seen John, because he had news. George Stanley-Holme, John's father, was actually his stepfather. John's mother had him by a previous marriage. He wasn't the soon-to-be Earl at all! Mr Land was "awfully bucked" because he had a son! Fish runs away to Wheatley to find him, and succeeds, and tells John. The story ends on a happy note, for it is Roberta's wedding day.