Twins June and Jennifer Gibbons speak only to each other in a language of their own creation. As young teens, they commit a violent crime. After 14 years in Broadmoor Psychiatric Institution, freedom visits them in a mysterious way.

George Vance, custodian of an agricultural museum near Aylesbury, receives news that is about to change his life. Much to his surprise, George inherits the Earldom of Ynys Enlli.