The series is named after a real challenge in celestial mechanics:

An alien race living on a planet with three suns. Because the gravitational interaction of three suns is mathematically unpredictable (the "three-body problem"), their world suffers from extreme "Chaotic Eras" that periodically destroy their civilization.

The series follows the consequences of a secret military project in China that sends signals into space to establish contact with aliens.

The story details how different factions of humanity react to the news of an impending invasion, ranging from those who welcome the aliens to those who seek to defend Earth.