Astronomers have spotted something that shouldn't be there: whole clusters of galaxies moving in eerie lockstep toward one patch of sky, as if something outside the observable universe were pulling on them. This film follows the researchers tracking that anomaly, nicknamed dark flow, through data from the cosmic microwave background and X-ray surveys of galaxy clusters. Cosmologists explain how the standard model predicts random motion for these clusters, and why a shared drift in one direction breaks that model rather than merely bending it. The film lays out competing explanations, from statistical noise and measurement error to the more radical idea that unseen structures beyond our cosmic horizon, remnants perhaps of a pre-Big Bang state, are tugging on everything we can see. Interviews with working physicists keep the claims tethered to actual data rather than speculation, and the film is honest about how contested the finding remains within the field. It ends without a resolution, because the observations themselves are still being argued over.