The last book in the Secret series goes back to the UK, and goes through all the right motions, with a mysterious castle, an abandoned town and mines, suspicious villains, secret passages and many of the usual trappings of a good Blyton adventure.

However, the whole thing feels slightly rushed, as if the author is not really relishing the story. We have some science fiction elements, with a mysterious metal with alarming properties, but fortunately the story doesn't really dwell on that. The way the villains are defeated feels a bit too easy.

An adecuiate addition to the series, but not really one of the most inspired. ( )