The writing career of Algis Budrys stretched over the second half of the last century, publication dates starting in 1954 and finishing in 1993. In that time he published eight novels along with many short stories. I used to own copies of three of the novels: Who?; Rogue Moon; and The Iron Thorn. All of them memorable, but the best-known of them was Who?: one of the few SF stories to achieve a much wider readership than SF fans, it was made into a feature film in 1973. As a result of occasional space-saving purges over the years I have kept only The Iron Thorn. A shorter version was first serialised in IF magazine in 1967 before the novel was published in the following year; an alternative title was also used, The Amsirs and the Iron Thorn.
The Iron Thorn begins in a small community on a bleak desert world. The people have lived, for as long as their collective memory can recall, clustered around a tall metal tower which they call the Iron Thorn. People can only survive, and crops will only grow, in the area surrounding the tower. Those wearing special metal caps can range further afield, but only in sight of the tower; go any further and they die of lack of air and freezing cold. The few caps are given only to those who hunt for food the enemies of humanity out in the desert; the Amsirs, human-sized flightless birds who make formidable opponents.
Honor White Jackson is an intelligent and rebellious young man on his first hunt, during which he discovers some shocking facts that were kept concealed from everyone except the hunters. This leads him on a journey during which he experiences a series of revelations about the nature of his world. That's really all I can say without posting spoilers, so all I'll add at this point is that, on reading for it the first time since the 1970s, I can understand why it survived my purges. It's a terrific story, exceptionally well plotted and written, and worth anyone's time to read, especially as it only runs to 160 pages. I read it in one sitting, because after reading the first page I didn't want to put it down. However, it is a little-known book, so for those who want to know what happens I'll continue the description below.
SPOILER WARNING – READ NO FURTHER IF YOU WANT TO READ THE NOVEL
What Jackson discovers is that the Amsirs are intelligent, carry throwing weapons similar to his, can speak, and want to capture humans instead of killing them. Feeling stifled by the limited nature of life around the Iron Thorn, Jackson rebels and sets off to the desert where he voluntarily surrenders to one of the Amsir. With the aid of clothes and breathing apparatus supplied by the Amsir, Jackson is taken across the desert and over the mountains to a huge, lush valley where the Amsirs live within the protection of their own, much larger, Thorn. There, he learns that the Amsirs want humans in order to gain entry to a much smaller version of the Thorn that stands beside the big one; there is a ladder to a closed door half-way up the small Thorn, but any Amsir who tries to open it is killed by the Thorn. Humans are not harmed, but so far none has been able to open the door.
Jackson manages to get the door open and discovers that the small Thorn is a functioning spaceship. After a rapid education-by-induction process he understands that he is on Mars, and that the two colonies of humans and genetically-engineered Amsirs were set up long ago as an experiment to see if life could be adapted to the planet. He flies the ship to Earth, expecting to find a high-technology civilisation, only to discover that there have been massive changes in the intervening period. The world is run by Comp, an all-pervading artificial intelligence that can instantly provide for any need. People now lead idyllic but pointless lives of leisure, focused on achieving status through social games (portrayed in a chillingly convincing and thought-provoking way), and Jackson once more feels himself out of synch with the life and rebels against the role the people want him to adopt.
Budrys, who died in 2008, had a reputation of being one of the more thoughtful and literary SF writers of his era. This reputation is fully justified by The Iron Thorn but, despite these qualities, the story remains as fast-paced and exciting as any. Highly recommended.