Lin Xinya, the campus belle, mysteriously takes an overdose of medication and dies by suicide. Everyone in her dormitory believes she took her own life because of depression. Her twin sister, Li Mengzhen, along with eight other people connected to the case, is dragged into a bizarre classroom in the Nether Abyss. A masked figure announces a deadly game in which they must collectively identify the culprit responsible for Lin Xinya's death. Anyone who makes the wrong accusation will face a brutal punishment. Suspicion and betrayal unfold one after another, while secret affairs are exposed in rapid succession. Who was the real mastermind? Beneath what appears to be a suicide lies a web of conspiracies. This deadly battle of human nature in a sealed space will uncover the entire truth behind the campus belle's death.