As with all Fighting Fantasies, this is a third-person multi-route adventure gamebook in which the reader takes on the role of a fantasy hero and has to solve puzzles, battle monsters and map routes to finish the book. The almost Buffy-esque storyline involves an evil wizard stealing a demonic book from a monastery in order to raise a powerful demon. The atmosphere is gothic, almost theological, with witches real and accused, hallowed places, saints and martyrs, pilgrims and monks, and some real aspects of medieval life, from bandits to plagues.
Among the later Fighting Fantasy adventures, this book stands out as containing some definite original ideas - the strong use of herblore adds a new twist to the item-gathering aspect of the story. It is genuinely multi-pathed, although there is only one "good" path through and the "wrong" paths soon end in disaster. The broad range of items one needs to acquire to complete it successfully makes for re-readability.
This is also, however, its drawback - the book requires far too much for successful completion. You'll need real-life as well as in-game luck (including surviving a 1 in 2 chance of sudden death), sky-high stats and a seemingly impossible Faith score to complete it. And the need for some of the items only becomes apparent too late, making it frustratingly easy to fall just because you didn't realise you'd need an antipoison, a raven and so on, until it's far too late. A clearer idea of what is needed from the start, would have tipped the adventure from frustrating to enjoyably challenging.