The Dark Forest (English translation, 2015) is the second book in a trilogy that began with The Three-Body Problem. I find these books long, too long to be honest, although after I've finished reading them they stick with me. I'm not sure why they feel over-long as I'm reading them. Odd.
The books must be read in order.
from the back of the book:
The Three-Body Problem gave English-speaking readers their first taste of China's most beloved science fiction author, Cixin Liu, quickly gathering as much acclaim in the United States as it had in China. The Three-Body Trilogy continues with the near-future speculative fiction masterpiece The Dark Forest.The LA Review of Books says, "Cixin Liu’s The Dark Forest takes up the Fermi Paradox as one of its central narrative and thematic problems," and concludes their positive review with this: "Why is the universe so uncannily, so eerily, so terribly quiet? Because in the dark forest, anything that makes a sound gets eaten."
Earth is reeling from the revelation of a coming alien invasion -in four centuries' time. The Trisolarans' human collaborators have been defeated, but the aliens have seeded the earth with sophons, subatomic particles that allow them instant access to all human information, so Eaarth's defenses are totally exposed to the enemy. Only the human mind remains opaque.
This is the motivation for the Wallfacer Project, a daring plan that grants four people enormous resources to design secret strategies, hidden through deceit and misdirection from Earth and Trisolaris alike. Three of the Wallfacers are influential statesmen and scientists, but the fourth is a total unknown. Luo Ji, an unambitious Chinese astronomer and sociologist, is baffled by his new status. All he knows is that he's the one Wallfacer that Trisolaris wants dead.
Strange Horizons calls it "even better than the first book". Kirkus Reviews says it's "a highly impressive must-read." SF Signal: "BOTTOM LINE: If you enjoyed The Three-Body Problem, read The Dark Forest. If you’ve ever thought about whether or not there’s life and intelligence on other planets, read The Dark Forest. Basically, if you’re a thoughtful human being interested in the universe outside of your own mind, read The Dark Forest.
#1 The Three-Body Problem