When a malfunction occurs aboard the luxury space cruise ship Avenue 5, it's up to engineer Billie McEvoy to warn Captain Ryan Clark, Avenue 5 owner Herman Judd and his right-hand-woman Iris Kimura that the incident may have a cataclysmic knock-on effect.
As Rav and her team meet with a NASA representative to plot a potential rescue mission, Ryan learns that Cyrus, an engineer working in a hidden part of the ship, has a surprisingly optimistic theory about the ship's future. Judd donates a lavish personal item to help commemorate a fallen crew member. Karen becomes a vocal advocate for passengers.
With Avenue 5 staff slacking in their customer service, Ryan offers Karen the opportunity to channel her unique talent for speaking the passengers’ language. Judd outlines the plan for a rescue mission and tasks Iris with organizing a vigil on Earth to raise the money to fund it. Rav endures a barrage of messages from the ship and handles an unruly press conference.
With Judd worried about his reputation, Iris arranges a meet-and-greet with several passengers in his luxury suite. Frustrated by a bridge crew with no answers, Ryan and Billie bond with the engineers below deck. Matt encourages Frank to become the man he always wanted to be.
Billie seeks her moment in the limelight after stepping in to help Ryan during the ship's newest crisis. Iris vets comedian Jordan Hatwal's material for the Halfway Home Party, which Judd has decided should go on as planned. Doug tries to get in the way of Mia's newfound sexual freedom.
As Avenue 5 celebrates the birth of a space baby, Ryan and Billie try to identify the source of an incessant beeping, and Judd shares his latest grand idea at Karen's passenger-crew liaison meeting. In the nation's capital, Rav appeals to the President for rescue funds but, in exchange, is faced with an ethical dilemma.
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.
While Karen oversees an effort to jettison non-essential passenger items, Billie tries to teach an inattentive Ryan how to dock the ship. Matt learns of Judd's plan to make the "ultimate sacrifice" by returning to Earth. Meanwhile, the passengers suspect all is not as it seems with the journey.
A search party commences for Matt, who's in hiding with a guilty conscience – and the airlock codes. Iris questions Karen about her rumored affair with Ryan. Rav seeks an apology from Judd for ruining her life, as chaos ensues when a seat on a rescue shuttle suddenly becomes available.
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.
When the ship crosses paths with a rogue space station, Ryan and the crew jump at the opportunity to socialize, while Billie angles for help with Avenue 5’s mounting eel problem. Then, after Rav discovers the true purpose of Storm Falcon’s mission, Ryan must steer his team through a difficult moral quandary.
Now stuck with an unsavory stowaway, Ryan and Billie lock down the ship – with potentially dangerous consequences. Meanwhile, Iris and Judd attempt to blackmail Lucas, Karen claws her way back to the top, and Frank fends off an attack.
After a failed revolt, the passengers put the ship’s leadership to a vote, bringing forth a pack of unlikely candidates. Meanwhile, back on Earth, the Office of the Other President proposes a plan that could spell doom for Avenue 5.
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.
With the ship divided, both sides find themselves in an all-out fight to survive. Then, Ryan takes part in a shotgun wedding, and Rav reaches a personal breakthrough.
