The Famous Five Five On Kirrin Island Again Enid Blyton

Kirrin Island belonged to George: it was her very own, and she felt aggrieved when
her father ‘borrowed’ it for one of his experiments. And to make matters worse,
he built a mysterious tower in the ruins of the old castle.

The Five couldn’t really understand Uncle Quentin’s wish to be left quite alone,
and as it turned out, it was a good thing that George took matters into her own hands
one night—otherwise there would have been no more adventures on Kirrin Island, and
Timmy would never again have been able to prove how intelligent he was.