First Broadcast on 2nd October 1978
Executive Producer James Gatwood
Produced by Don Leaver
Directed by Peter Duffell
Adapted by Gloria Tors
Guest starring:
Shane Rimmer, Leslie Dwyer, Thelma Whiteley,
Ben Aris, Peter Copley, Julia Silk, Simon Adams &
Andy Campbell.
The Famous Five spend their holidays at Finniston Farm. On arrival, they are greeted by Mrs Philpot and her identical twins, Henry and Harriet who take an instant dislike to the Five. They also meet two American guests; Mr Henning and his son, Junior. Mr Henning plans to buy antique pieces from the farm and sell them in America. The family's hot-tempered Great Granddad feels the antiques should remain in England.
Mr Henning and Junior prove themselves a nuisance to the household by rudely ordering around Mrs Philpot. Sympathetic to Mrs Philpot, the Five offer to help with farm chores. When Junior demands breakfast in bed, George teaches him a lesson, making him agree to not slave Mrs Philpot thereafter. This wins the hearts of the Harries and they make friends with the Five.
Anne and George visit a nearby antique shop, owned by a Mr Finniston, who tells them about a secret passage from Finniston Castle to an old chapel and cellars where royal treasure might be hidden. The girls excitedly reveal the news to the boys and the twins. Together, they plan to hunt for the cellars on the farm. They come across the castle's kitchen midden and realize they are close to finding the treasure.
Junior spies on them and rushes to break the news to his father and his father's friend Mr Durleston, who decide to excavate the castle site, find the fortune and sell the goods in America. Mr and Mrs Philpot consent to the excavation, much to the dismay of the children. The children dig around the site, hoping to beat the men in finding the treasure. Initially they are unsuccessful but the twin's dog Snippet and their jackdaw Nosey lead them to a burrow, beneath which the secret passage stretches out.
The children discover the cellars and the treasure, only to become trapped inside the tunnel when the entrance caves in. They take another way and reach a trapdoor under the old chapel, which is now used as a storehouse. The farmhands Bill and Jamie hear their shouts and let them out. The children get back to the farm and tell their exciting story to the astonished adults. The next day, Mr Henning and Mr Durleston try to trick the Philpots into believing the site has no treasure and offer them a meagre amount. However, Mr Philpot, backed up by his granddad and Mr Finniston, declines the offer, making it clear they will excavate the site themselves and no longer want the Americans to stay. The adventure ends with Julian, Dick, Anne and George along with Timmy planning to stay at the farm to observe the excavation of the treasure.