The Three-Body Problem Series by Cixin Liu

Summary:

The Three-Body Problem series by Cixin Liu is a hard science fiction trilogy centered around humanity's first contact with an alien civilization, the Trisolarans, whose planet's unstable orbit threatens their existence. As the two civilizations interact, a conflict unfolds, exploring themes of science, technology, and the fate of humanity.

The Three-Body Problem
A physicist uncovers a secret alien communication that leads to Earth's first contact with the Trisolaran civilization, setting off a chain of events with far-reaching consequences.

The Dark Forest
Humanity prepares for an inevitable alien invasion, with a brilliant strategist using a theory of cosmic sociology to defend Earth from the Trisolarans.

Death's End
The final showdown between humanity and the Trisolarans unfolds, with existential threats and the ultimate fate of the universe at stake.