Astronaut and physicist Ulrich Walter joins a group of cosmologists to retrace the history of the universe from the Big Bang to the present, tackling the question of what makes up the 95 percent of the cosmos that emits no light. The film moves chronologically, opening with the single point of infinite density that models place at the origin of everything, then through the so-called Dark Ages before the first stars ignited and lit the universe for the first time. Cosmologists lay out the evidence for dark matter, the unseen mass that keeps galaxies spinning fast enough to fly apart under ordinary Newtonian gravity, and walk through why the visible stars and gas we can photograph account for only a small fraction of what must be out there. Animation and simulated star fields stand in for the eras no camera could ever record, while interviews carry the argument through structure formation, galaxy clusters, and the open question of what dark matter actually is.