Whilst T.H. White is best known for his sequence of Arthurian novels, The Once and Future King, he did write many other novels such as this novel, The Master which was published in 1957.
This Science Fiction Adventure novel follows a pair of Eleven-year-old twins & their dog who are marooned on the seemingly bleak island of Rockall. However, it is soon revealed that the island is actually ruled by a mind-controlling genius bent on world domination.