This is book number 1 in the The Three-Body Problem Series series.
In the midst of the Chinese Cultural Revolution, a young scientist sends a message into the cosmos that brings a desperate, far more advanced civilization hurtling toward the Earth, and humanity begins planning for a Doomsday Battle that won't happen for four hundred years. There are a million reasons to love Liu's storytelling in this first book of his Three-Body trilogy, but his ability to keep the pace and tension humming while also keeping the aliens almost entirely off-stage utterly blew my mind.
The Three-Body Problem is the first chance for English-speaking readers to experience the Hugo Award-winning phenomenon from China's most beloved science fiction author, Liu Cixin.
Set against the backdrop of China's Cultural Revolution, a secret military project sends signals into space to establish contact with aliens. An alien civilization on the brink of destruction captures the signal and plans to invade Earth. Meanwhile, on Earth, different camps start forming, planning to either welcome the superior beings and help them take over a world seen as corrupt, or to fight against the invasion. The result is a science fiction masterpiece of enormous scope and vision.