In this episode, as Voyager crosses an enormous expanse with absolutely no stars visible in any direction, they encounter local denizens whose home is being used as a dumping ground for toxic waste by the Malon.
En route towards the Alpha Quadrant, the Federation starship Voyager is forced to travel through a sector of space, "the void", where starlight is completely shrouded, creating a dense black cloud. The journey through this sector will take two years, but only two months into the travel has set the crew on edge. Left with nothing to do in the empty darkness, Captain Janeway has taken the time to reflect on their situation, feeling intense guilt for her choices that left the crew stranded in the Delta Quadrant.
One day, all power to the ship is knocked out, caused by an external field. They discover one of several alien intruders aboard Voyager and are able to capture one. They manage to restore power, discovering themselves surrounded by three smaller ships, but soon these are chased away by a larger ship of different design. Its pilot introduces himself to the Voyager crew as Emck, a Malon. After learning of Voyager 's plight, he offers to lead the ship to a vortex that can lead them to the other side of the void, in exchange for the alien prisoner. Janeway refuses until she learns more.
The alien in Sickbay is healed, and apologizes for his species' actions. They are a people that are trying to fight the Malon, as they dump toxic theta radiation into the vortex, harming their species. Janeway attempts to arrange a deal with Emck, to provide him with Federation technology to recycle the theta radiation into useful energy and matter in exchange for passage to the vortex, but Emck refuses, as this technology would ruin his livelihood as a waste hauler.
Janeway comes to learn of the vortex' location from the night alien. She attempts to order the crew to send Voyager through the vortex while she stays behind in a shuttlecraft to destroy it, ending the Malon's use of the void as a dumping grounds. The crew refuses, acknowledging that they do not blame Janeway or harbor resentment for her actions that stranded them in the Delta Quadrant. Together, they come up with a second plan, to launch torpedoes shortly after entering the vortex, riding out the shockwave as the vortex is destroyed. As Voyager approaches the vortex, they are attacked by the Malon, but soon the smaller alien ships reappear and distract the Malon long enough for the ship to enter and destroy the vortex. The journey leaves them but a short distance from the edge of the void and within minutes, the Voyager crew is elated to see stars once again.