First Broadcast on 3rd & 10th July 1978
Executive Producer James Gatwood
Produced by Don Leaver
Directed by Peter Duffell
Adapted by Richard Sparks
Guest starring:
Michael Hinz, Sue Best, Frederick Von Thun,
James Villers, Oscar Quitak & Donald Morley.
Julian, Dick & Anne go to stay with their Aunt Fanny, Uncle Quentin and Cousin George and plan to visit Kirrin Island for their school holidays, which is owned by George but Uncle Quentin is using the island to conduct some secretive scientific experiments.
George is frustrated and unhappy when she has to leave her beloved dog Timmy with someone else in the village because her father doesn't want him in the house.
Uncle Quentin has built a tower on the Island and signals home each morning and night.
Johnson, a mysterious man who previously worked for the Government is very interested in the top secret experiments and along with a local man Mr Curton sets out to steal the secret formula for alternative energy and kidnap Uncle Quentin.
The Five discover a secret tunnel near Mr Curton's house which they realise connects the island to the mainland and use it to rescue Uncle Quentin.
During the adventure, Timmy plays an important part in rescuing Uncle Quentin from the kidnappers and Uncle Quentin allows him to return to the family home.