The Robinsons are two respectable middle class parents living with their children in a suburban house in Acacia Avenue. Preferring to holiday every year in Bognor, they are pressed into booking a cruise for their annual vacation and thereby leaving their teenage children free run of their house. As the youngsters enjoy their newfound freedom and discover the angst of teenage life, Mr. and Mrs. Robinson begin to have second thoughts about their cruise and decide to return home early.
A stray World War Two bomb releases the ghost of the 3rd Earl of Chaunduyt after 400 years. A visiting professor, while wooing the beautiful Lady Mary, daughter of the present Earl, finds him an ally in his fight on behalf of the villagers to protect their ancient rights against a meddling newcomer.