The Dark Forest is the second book in Cixin Liu’s Three Body Problem trilogy. I reviewed the first book here. In the second book the tone changes from being a hard bitten conspiracy story to a fully-blown space opera.
The Dark Forest of the title is a metaphor for a philosophical thought experiment. The universe is thought to be teaming with life. Each civilisation is like a hunter in a dark forest. Revealing oneself, leaves one open to being killed by another hunter. Since you don’t know a hunter’s intention it seems better to be quiet. Conversely if you become aware of another civilisation there is a strong incentive to get them before they get you.
Unlike the first book, The Dark Forest takes place over centuries as the protagonist is put into cryogenic hibernation and then woken centuries later. Living in the future provides a warning for readers against the perils of having all parts of our life automated and connected – it delves into similar themes as Michael Crichton’s Runaway.