Lord Cuthbert Gansville-Stubbs lives in luxury on his estate at Havercoyne Grange together with wife Agatha, sister Carlotta, brother Damian, aunt Prudence - who makes everyone's life a sheer misery - and, of course, his beloved racehorses. Cuthbert, however, has a conscience which troubles him slightly and his dilemma is worsened by Carlotta's schemes to rid the household permanently of aunt Prudence. The Medici Squadron, however, manage cunningly and ingeniously to infiltrate the Grange in order to discover many thought-provoking facts.