While on a charting mission, the Federation starship Enterprise, under the command of Captain Jean-Luc Picard, discovers a zone of pure blackness in space; probes launched into the area simply disappear. As they study it further, the zone expands and soon envelops the Enterprise, leaving them in a black void with sensors reporting nothing outside. Picard orders the ship on a return course but they find that they cannot escape. They leave a stationary beacon behind them, only to have it reappear ahead of them.