The first half of this obscure 1968 novel was truly compelling, weird, suspenseful; I loved it. The second half was less good, as the book turned into a fairly conventional action thriller. Still, overall, it was quite good.
The hero is an unnamed 41-year-old British art critic residing in Spain, where he is writing a book on Diego Velasquez. Since his schooldays, he has had a weird compulsion: whenever he sees a building, he feels compelled to climb it. Occasionally his strange obsession has gotten him into trouble, like the time he fell from a high building in Copenhagen and broke his pelvis.
His mostly quiet life is suddenly upset when an old school acquaintance drops in on him and offers him a large sum of money for a mysterious job: to use his nightclimbing (and leaping) skills to gain entrance to a deserted house in Paris and there to steal something. At great risk to himself, he does this, but the outcome is not what he expects. And then his employers offer him more money for a mysterious task that is eventually revealed to be climbing a mountain in Greece and, once inside the Cave of the Cyclops, making a death-defying leap in total darkness over a twelve foot gap - to open a sealed door with a strange key and get.... what? If he refuses, his employers will kill him. If he fails, he'll die. If he succeeds, they'll probably kill him anyway.
Around 100 pages in, it struck me that this was a very 'male' book. All the characters were male; all the deeds and actions were manly. The author must have noticed this too, for about halfway through he introduces an unfortunate subplot involving a damaged woman character, Claudie, a damsel in distress whom the hero must save from being delivered to a lascivious Bulgarian official. This is around the point where the book, for me, went from stellar to just OK.
I won't spoil the book by saying anything about what ultimately happens, but if you like obscure old books with a few thrills and chills, you could do worse than this one. I'm curious to read his other two next.