Voyager is trapped inside the event horizon of a quantum singularity while Janeway chooses between Carey and Torres for chief engineer.
Voyager detects a ship caught near a quantum singularity and moves to help, only to find that the vessel is a distorted image of Voyager itself and that the ship is already trapped inside the singularity's event horizon. Escaping means finding the narrow opening through which they entered before the surrounding forces tear the ship apart.
The crisis plays out against a dispute over who should be chief engineer. The Starfleet candidate is Lieutenant Joe Carey, while the former Maquis B'Elanna Torres has a fierce temper and has already broken Carey's nose in a fight. Torres proves herself during the emergency, working with Janeway on a shuttle mission to widen the way out, and Janeway gives her the post.