Ladybourne Hall, the Great House of Sir Humphroy Ainsley, provides the scene for two children to amuse themselves (outside London in 1690) while their architect father awaits Sir Humphrey, his patron, for final approval on plans for a new house. Geoffrey is supposed to be studying for (for Oxford, alma mater of his idol, Sir Christopher Wren) but he takes to other things: cock fighting and betting and measuring another site for the new house. Barbara helps lay a pebble foundation and finds a friend in Elizabeth, Sir Humphrey's daughter who is not supposed to associate with strangers. A missing purse, a recurring mad woman (who sets fire to the house Jane Eyre style), and two boys who run away to London are also involved, and small details (virginals and highwaymen, the rarity of toothbrushes, the request for forks at an inn) add verisimilitude. The interest is all external, the story merely an elaborate shell.