'The Pilgrim's Regress' is an intriguing allegorical book by CS Lewis, best known for the 'Narnia' series. It's obviously meant to be a parody of 'Pilgrim's Progress'; the hero is called John, and he - like Bunyan's hero - sets out on a long journey, where he meets various characters and dangers before discovering the reality of God. John's upbringing is in the land of Puritania, where the 'Landlord' is a shadowy being who has produced lengthy rules that everyone is supposed to follow.
However the language is more modern (and thus easier to read) than Bunyan's, and the people John encounters are not so much temptations of the flesh as philosophies of life, from the middle ages up to the 20th century. He has to find his way through romanticism, Marxism, even common sense, and realise that the only answer to his ongoing search is in Christianity.
Running through the book is John's longing to find an island, which he's seen in the distance. Lewis, in his introduction to the book, says that he realised after writing it that not everyone has this deep, almost nostalgic longing for something unobtainable. Nor is everyone aware of the many pseudo-Christian (and unChristian) philosophies that have often led people astray through the ages. So he gives an outline of what each allegory means at the start of each chapter, making it simpler for ordinary people (whom Lewis would probably consider uneducated!) to understand.
It's still a fairly academic book, peppered in places with Greek and Latin quotations, and unsubtle references to lesser-known theorists. I didn't understand them all, but that didn't detract from the overall enjoyment of the book, or the points being made.
Recommended in a low-key way for anyone with at least some classical education and an interest in this kind of book.