The Planet Express crew go on a mission to rescue animals on Vergon 6, a planet that was mined hollow of the dark matter that filled it for fuel, and is on the verge of collapse. On the way, they meet Zapp Brannigan, who Leela is initially flattered to meet until he refuses to help them save the animals of Vergon 6 as per the law and imprisons them instead. That night, Zapp tries to seduce Leela, succeeding in getting her to sympathize with his loneliness as a captain, and she has sex with him out of pity. The next day, Zapp decides to release the crew and allows them to travel to Vergon 6, believing Leela will come crawling back to him. While collecting the animals, Leela discovers another creature not on their list and decides to save it as well, naming it Nibbler, who subsequently devours all the other animals they saved. The planet begins to collapse and the crew find their ship is out of fuel. Leela refuses to accept Zapp's help when he tells them Nibbler must remain behind, and the crew resign to their fate until Nibbler excretes a pellet of dark matter, which gives them enough fuel to escape before the planet implodes.