It is the 23rd century. Two hundred years before, a small planet had entered the Solar System, captured the Earth and the Moon, and pulled them out of their orbit into interstellar space. The controlling intelligences of the wanderer were enigmatic mobile Pyramids measuring 35 yards on each edge and possessing incomprehensible powers. One of them planed off the top of Mount Everest and had sat there ever since. Every attempt by humanity to attack the Pyramids and their planet ended in failure, and the Sun had become just another star in the night sky. The Earth remained habitable because the Pyramids turned the Moon into a mini-Sun. This faded over time and had to be relit every five years, causing a cycle of heat and cold which played havoc with the Earth's climates, sea levels and agriculture.
Humanity had suffered badly from these changes and the population had dropped to just 100 million, most of whom had to survive on 1,000-1,500 calories a day. The perpetual hunger had led to a low-energy lifestyle in which people lived their lives slowly within an elaborate structure of approved social behaviour, with every word and gesture being carefully stylised (the authors have some fun with this). Displays of emotion were solecisms, as was any attempt to take more than one was entitled to. Meditation was the most popular pastime, with the aim being to achieve "Translation": when someone reached the state of having a perfectly blank mind, a swirl (known as an "Eye") formed in the air above them and they disappeared in an instant.
Not all of humanity fitted into this pattern. A small minority, called "Wolves" by the rest, lived selfish, competitive, aggressive lives. When discovered they were seized and ritually killed (in a particularly unpleasant way) by the majority.
Glenn Tropile was a young misfit who, despite his traditional upbringing, had discovered and deliberately encouraged Wolfish tendencies in himself. He was caught and sentenced to death, but managed to escape with the aid of the members of a settlement composed entirely of Wolves, which had been able to establish itself and remain hidden from the rest. The Wolves ate well, being efficient scavengers, and they did not meditate. But Tropile could not give up this one aspect of his former life, and was duly Translated.
More of the plot cannot be revealed without spoiling it for new readers, but suffice to say that the Pyramids had a particular use for humanity which eventually proved to be their own weakness. The Wolves lead the resistance against them, taking the battle to the Pyramids' planet.
Pohl and Kornbluth were among the leading SF writers in the 1940s and 1950s. They wrote separately but are probably best remembered for their collaborations, of which "The Space Merchants" is the most famous. "Wolfbane" was first published in 1959. The plot was a departure from traditional genre themes: to start a novel with the Earth being wrenched out of the Solar System, leading to the death of 99% of humanity, was unusual to say the least. Because the human culture described is quite alien to us (although not unlike that of parts of ancient China) the story has not dated in the same way as most SF of this period. It could have been written today, although a modern author would certainly make the story stretch over far more than its 160 pages and would spend a lot more time in developing the characters. I'm not at all sure that this would be an improvement: "Wolfbane", like so many of the products of the "Golden Age" of SF, is a novel of ideas and concepts to stretch the imagination. In that respect it still works today, benefiting also from being so fast-paced that it's difficult to put down. It's well worth the brief time needed to read this little classic.