The Three-Body Problem (Remembrance of Earth's Past #1)

Four decades later, Beijing police ask nanotech engineer Wang Miao to infiltrate a secretive cabal of scientists after a spate of inexplicable suicides. Wang's investigation will lead him to a mysterious online game and immerse him in a virtual world ruled by the intractable and unpredictable interaction of its three suns.

This is the Three-Body Problem and it is the key to everything: the key to the scientists' deaths, the key to a conspiracy that spans light-years and the key to the extinction-level threat humanity now faces.