It was the year of Trafalgar and Tom couldn't wait to leave childhood behind and join 'Nelson's' fleet, whatever his twin sister felt about being cooped up still at home. Castor's Away is about the battle of Trafalgar during the Napoleonic wars and features the Henchman family: the father, who is a family doctor, his wife, and their three children. When the family comes to spend some of the summer holidays with their aunt, who lives on a farm near the sea, the children find a soldier who was washed ashore from a transport ship which was wrecked by a storm and complications arise.