A miniseries inspired by the real-life Project Orion from the Kennedy era, it takes place in an alternate 1963. The government sends 600 volunteers into space, telling them that they fear the Cold War will result in the destruction of Earth. Men, women, and children are put inside a a self-sustaining spaceship on a 100 year trip to colonize a planet orbiting Proxima Centauri.
At year 51 (i.e. today), they experience the first homicide since the experiment started and start to question the true nature of their mission.
Turns out they’re not actually in space at all! Whoops!