A duplicate Voyager from a space anomaly causes a mirror-image crisis.
Voyager is caught in a spatial rift that creates a duplicate of the ship and its crew, and both versions must work out how to survive as the Vidiians attack. A newborn child, the first to be born aboard Voyager, becomes central to the story.
The episode is a well-regarded action story and a key one for the second season, because it introduces Naomi Wildman, a recurring child character. It also contains a famously difficult moment for Harry Kim, and it uses its doubled-ship premise to create a tense and dramatic climax.