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 Mulcair manages the situation from mission control back on Earth, Matt Spencer, the head of customer relations, tries his best to calm frayed nerves on board, and persistent passenger Karen Kelly discovers the crew may know more than they're letting on.

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 (Josh Gad) donates a lavish personal item to help commemorate a fallen crew member. Karen becomes a vocal advocate for passengers. Mia and Doug receive marital counseling from Matt.

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. 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.

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. 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. Chaos ensues when a seat on a rescue shuttle suddenly becomes available.