When a malfunction occurs aboard the luxury space cruise ship Avenue 5, it's up to engineer Billie McEvoy to warn Capt. Ryan Clark, owner Herman Judd and his right-hand woman Iris Kimura that the incident may have a cataclysmic knock-on effect.

Judd enlists Ryan to help charm Harrison Aimes, an uber-wealthy passenger who has a strange effect on Judd. Meanwhile, the passengers become transfixed by a divine image circling the ship and Rav deals with the fallout when the ship's moral quandary hits the media.

After five long months, the passengers of Avenue 5 eagerly await their impending return to Earth­­ while behind the scenes, Ryan and the crew struggle to find a way to reveal the much longer timeline of their journey home. Later, a disgraced Karen comes to blows with a newly famous Frank.

With the ship facing a fiery threat, Billie hatches a plan that could just save some of the passengers… and the eels. Meanwhile, Iris makes a risky bid on Earth, Ryan finds himself in the middle of a three-way couples’ quarrel, and Mia shares some shocking news with Doug.

With a "new" leader at the helm, life on deck reaches a semi-status quo – until the discovery of a mysterious blip and dissident uprising threaten to upend the passenger’s tenuous peace. Later, life imitates art as the shocking conclusion of TV’s Avenue 5 puts those aboard the real ship in peril.

The crew turns to a Judd-designed ranking algorithm to deal with their latest threat. As Ryan’s rating mysteriously tanks, Billie searches for her more worthy counterpart, and Judd attempts to make amends with an estranged Iris.