The 1640s, the time of the English Civil War. Colonel Beverley, a Royalist, squire of Arnley and High Keeper of the New Forest, leaves to join the King's army. He dies at the Battle of Edgehill, leaving his two sons and two daughters in the care of their Aunt Judith. A troop of Parliamentary soldiers and their Leveller preacher, Abel Corbould, come to Arnley. The four Beverley children are smuggled out of Arnley, taken to his forest home and hidden there by Jacob Armitage, a royalist forester. The children encounter various adventures, become involved with the family of Heatherstone, Parliament's new Intendant of the New Forest and eventually join a conspiracy to help King Charles, who has escaped from captivity.