The climactic scene of "Paradise" unfolds with a flashback to twelve years prior, where the construction of Sinatra's metropolis is in full swing. Inside the locker room, laborers engage in idle chatter, their conversation veering towards lighthearted remarks about everyday banter. Trent, the supervisor, persuades Adam, played by Cornelius Macarthy, to swap his rations for some of Trent's own. Adam, ever the guide, demonstrates the proper way to savor the food to Trent (Ian Merrigan). Later, Trent reciprocates Adam's kindness with a bottle of West African beer, a gesture that delights the worker.
Among the bustling workforce, one laborer struggles with respiratory distress. Trent confronts Anders (Erik Svedberg-Zelman), confronting him with traces of arsenopyrite, a toxic mineral, found on the site. Trent insists that they halt the construction to avoid further jeopardizing the workers' health. Anders expresses concern about compromising the structural integrity of the city, to which Trent responds that continuing will only lead to more illnesses among the workforce. Anders assures Trent that he will reassign his men and personally address the issue. However, when they meet again at the entrance, Anders informs Trent of his termination, pledging to implement safety measures such as masks for the workers.
Trent, curious about the project's true purpose, queries Anders. Anders reveals that they have intelligence suggesting an impending event of significance. Back at his home, Trent delves into research and attempts to reach out to Adam. His investigations culminate in the creation of a 3D-printed firearm, which he ultimately uses to shoot President Cal Bradford (James Marsden).
Returning to the present narrative, Sinatra (Julianne Nicholson) grants Xavier Collins (Sterling K. Brown) access to a recording of Teri, hinting that he might want to check on his daughter's wellbeing. Stepping outside, Xavier instructs Robinson (Krys Marshall) to release the captives, asserting Sinatra's innocence in the President's murder. Their discussion turns to the DNA evidence, with Robinson suggesting they reinvestigate the day of arrival. Xavier acknowledges Sinatra's custody of his daughter while Henry Baines (Matt Malloy) addresses the citizens, striving to quell their anxiety. Sinatra orders her team to erase all data from a tablet, oblivious to Jeremy Bradford (Charlie Evans) reading from the very same device outside. Henry speculates that foul play may have been involved in Cal's demise.
Dr. Gabriela Torabi (Sarah Shahi) endeavors to soothe Sinatra, who brushes aside her efforts, believing them futile. Jane Driscoll (Nicole Brydon Bloom) sits with Presley (Aliyah Mastin), discussing Billy with her. Sinatra phones Jane, torn between decisions regarding Presley, who possesses damaging knowledge. She emphasizes the importance of discretion, yet Jane inquiries about the President's video games, hoping to procure a Wii for Presley. Sinatra denies her request, urging caution. Jane terminates the call.
Xavier returns to the President's chamber for a closer inspection, uncovering a CD inscribed "For Jeremy." As he listens to Cal's voice narrating the creation of a mixtape, Xavier recalls a significant number mentioned in connection with a cigarette. Meanwhile, Robinson seeks Gabriela's assistance, revealing that all residents underwent psychological evaluations post-relocation. Robinson requests specific consultation records, which Gabriela initially refuses to hand over but eventually succumbs to Robinson's persistence.
Xavier heads to the library, while Gabriela and Robinson scrutinize the crowd. Gabriela declares that something is amiss if the contents of the file are accurate. Jane dispatches a message to Sinatra, informing her that the issue has been resolved. Gabriela proceeds to the restaurant, where she invites Maggie (Michelle Meredith) to join her for some companionship. Robinson subsequently joins them and holds Maggie at bay with a gun. Meanwhile, Xavier uncovers a book containing Cal's code, titled "The Man Who Kept The Secrets." Gabriela reveals to Maggie that her identity is a facade.
Xavier stumbles upon handwritten notes from Cal, detailing the recordings. Maggie claims that Cal coerced her into participating. Suddenly, Xavier is felled from behind. Trent recognizes that Xavier doesn't recognize him and admits that it's a complicated tale.
Flashing back, Adam finally responds to Trent's persistent calls, instructing him to stop. Trent views it as destiny that he'll be nearby when the time comes. Adam confesses that he's dying, but Trent already knows this. When the prisoners learn about the impending wave, they riot.
Escaping the chaos, Trent disguises himself as a policeman. He tricks two individuals into the woods and eliminates them, taking one's place. Later, he discovers Maggie outside in a car, indulging in junk food. Trent tells her that she might be the sole individual in the world at the right place and time. As they reach the gate, Trent simulates a medical emergency.
Trent confronts Xavier, revealing that he infiltrated the facility and intended to complete his mission. He became comfortable there and believed he deserved to live and survive for those who built the place but were excluded. Trent's perspective shifted when Cal approached him in the library to inquire about making a mixtape. At that moment, Trent knew he had to finish what he started.
In another flashback, Xavier tells Cal that he'll forgive him when he can sleep peacefully again—a state he believes will only come when Cal is deceased. Trent assaults Cal on the balcony. Cal marks an X on a cigarette pack with his blood before Trent attacks and finishes him off.
In the present, Trent informs Xavier that he can reveal to everyone who did this and why. He thanks Xavier for the book, acknowledging that it showed him the way out but he lacked the resolve. Trent believes that whatever remains of the world deserves to know the truth. He departs, leaving Xavier behind. Robinson arrives to liberate Xavier, who decides to pursue Trent. They eventually catch up with him.
Trent asserts that they had a chance to rebuild a better world down there but turned it into a prison. He wants people to know that the place is just a gravesite, which will soon be his as well. Trent plummets to his death.
Xavier then visits Sinatra to inform her about the librarian, inquiring about his daughter's whereabouts. Sinatra apologizes, stating that she never intended for the situation to escalate to this point. Xavier begins to unravel, shooting Sinatra's guards before pointing a gun at her head. Jane enters the room and shoots Sinatra, assuring Xavier that Presley is safe and with Brooks and Rainey.
When they're alone, Jane confesses to Sinatra that Xavier was intent on killing her and that she's no longer of use to her dead.
Jane firmly believes that Sinatra faces a lengthy and arduous road to recovery. She reflects that perhaps she should have gifted her the Wii to keep her spirits high. Meanwhile, Xavier manages to reach his children and engages in a conversation with Robinson about Sinatra's condition. Both are aware that her absence will necessitate someone stepping into her shoes. Robinson, who has been immersed in a thought-provoking book, contends that they must venture beyond their comfort zones to comprehend the current landscape. Xavier, however, expresses hesitance, citing the myriad of challenges they've already endured. Robinson persists, asserting that they must confront reality head-on and understand what lies ahead.
Later that evening, Xavier has a heart-to-heart with Presley, who urges him to bring Teri back home. Elsewhere, Jeremy listens intently to a mixtape thoughtfully curated by Cal. Driven by resolve, Xavier decides to embark on a quest to locate Teri. Cal, sensing Jeremy's contemplation, urges him to take matters into his own hands and reshape the world to his liking if he finds it unsatisfactory.
Gabriela finds solace in the bustling atmosphere of the restaurant, while Henry strives to address the crowd, eventually resorting to raising his voice to command their attention. In a poignant scene, Sinatra rests in the hospital, while a stark contrast is drawn as Jane enjoys a game of Wii at home, miles away from her ailing friend. Finally, Xavier takes to the skies, piloting a plane with a renewed sense of purpose and determination.
