In 1998, astronomers found that the universe is not just expanding but expanding faster over time, a result that won its discoverers the Nobel Prize for Physics and left cosmology with an unexplained force behind it: dark energy. The film traces how astronomers reached that point, starting with Vesto Slipher at Arizona's Lowell Observatory, who found that 12 of the 15 spiral nebulae he studied showed redshifted light, a sign they were racing away from Earth. Edwin Hubble followed up with the Hooker telescope in Southern California, using pulsating Cepheid stars to measure galactic distances and showing that farther galaxies recede faster, the relationship now called the Hubble Constant. That finding forced Einstein to abandon his cosmological constant, the fudge factor he had added to keep the universe static, which he later called his greatest blunder. Present-day footage follows work at Chile's Paranal Observatory, a facility in the Atacama desert that draws two megawatts of power collecting photons from galaxies, black holes, and the edge of the visible universe.