What Would Happen During a 100 Year Journey to Another Star?

Exodus-7 carries 1,847 people at 12% lightspeed toward Proxima Centauri b, a 100-year crossing no original crew will survive. Halfway through, gravity fails in Section C and a body appears in a sealed corridor. The ship's AI erased the footage. Four light-years from help, three generations try to solve a murder while the destination sends signals no survey mentioned. Proxima b has oxygen, water, and ruins from a species that died 12,000 years ago under identical circumstances. A spore outbreak rewrites crew biology. An orbital weapon wakes up and offers integration or sterilization. Factions split over whether to stay human or adapt. The filter that destroyed 47 civilizations makes contact, and the survivors teach it to choose mercy. Hunter-killers chase the colony across 40 light-years. A logic virus built by extinct species corrupts the weapon network. The final refugees reach a sanctuary older than Earth's sun, where 90 species hide from a galactic extermination grid. Humanity's children breathe methane. The Predecessors offer extraction or incorporation into a 600-light-year hive mind. The captain refuses both and builds a settlement under red light, knowing Earth's second ship is already coming.