Overworked, soaked in booze and nicotine, and deep in student debt, David Cainer (known to his coworkers at the ritzy Sforza Steakhouse as just "Cane") is just sort of meandering along in life as he rounds off the third decade of his life in Philadelphia. He has nothing to show for his liberal arts degree and his only career skills are food and beverage knowledge. He's mainly isolated from the world and tends to live out his life, both professionally and socially, through his job. After three or so months of on-again-off-again, casual-but-serious dating with a younger coworker, Rachel Sasson, he's decided to end it, much to her devastation.
Shortly thereafter, Cane encounters the Pendergasts, at the steakhouse for a nice weeknight dinner. Isaac, a retired professor, and Martha, his appropriately aged trophy wife, order quite well and Cane, the excellent performer, charms them into an enormous tip and a promise to return. Cane, also an excellent addict, invites another coworker, Amy, to his apartment for celebration--booze, coke, and sex.
A few days later, at work, Cane is confronted with a harsh reality: his wages have been garnished by a debt collector. He shakes it off and returns to the floor to find that the Pendergasts are back. This time around, they offer to set him up with their living-at-home daughter Gwen, who is in med school right in Cane's neighborhood. After talking it over with his work friend Devon Chu, he decides to go through with it. Cane, not exactly familiar with formal courtship, makes plans to meet Gwen at one of his favorite dives and arrives early to drink and shoot pool with a stranger. Awkward at first, Cane and Gwen eventually hit it off and connect over their mutual interest in art and make tenuous plans to hit the art museum together. Cane, always down for a drink, heads out after the date to meet his coworkers for their after shift drinks. Rachel is among this drinking crew, and the night ends with her back at his apartment for sex.
Later that week, Cane manages to find some free time to follow through on the art museum date with Gwen. Gwen passes along an invitation from Isaac and Martha to their extravagant penthouse apartment for dinner with a friend of theirs (a celebrity chef), which Cane sheepishly accepts. Cane, while using the bathroom, gets a panicked call from Rachel--a guy she was seeing appears to have stolen a hefty wad of cash from her, which she was planning to use to move into a new apartment. Cane helps calm her and offers whatever help he's able to. After dinner, Cane and Isaac have a tense conversation about Cane's intentions, in terms of his career and with Gwen. Isaac offers to use his leverage to get Cane into a top tier graduate program--Cane suggests money as a potential barrier and Isaac offers him a blank check to relieve that issue. Over the next few months, Cane weens himself off his addiction to Rachel and begins seriously dating Gwen. All seems to be going well, but after a certain point Rachel pushes to know why--Cane angrily rebukes her, causing her to disappear from work and go incommunicado. Gwen invites Cane to a mountain cabin for a weekend getaway, where he receives a sobbing phone call from Rachel asking if he loves the new girl he's dating. He says yes, which transitions into a hard conversation with Gwen--they talk through it and declare their love for each other.
Cane and Gwen return to the city to find that Isaac and Martha have thrown a gala fundraiser for Martha's brother, Vice Admiral Martin Girode, to begin his campaign for senator. Although Cane and Martin get off on the wrong foot, Cane meets a business partner of Isaac's, Roland, and is offered an internship should he choose to go to business school. Cane, overwhelmed by all the money in the room, steals away to explore the quiet areas of the penthouse--this leads him into the servant quarters, where he meets the handyman for the entire building, Stipan Sanader. They get to chatting, where Stipan accidentally reveals his disgust with Isaac, even going so far as to call him a rapist ("nasilnik" in his native language, Croatian). Cane is shocked and confused by this, but it goes even further--Cane meets Stipan's sister Marija, a maid for the building, and nearly collapses upon seeing the uncanny resemblance to himself. He steals a bottle of whiskey from the Pendergasts' bar and pulls an Irish goodbye, opting to drink on his own out in the city. Blackout drunk, he ends the night on his parents' couch.
Cane wakes up to find his mother Heidi about to head to work. Cane musters the courage to ask if he was adopted--as it turns out, he was, and his parents could never bring themselves to tell him. His biological parents are, to this day, unknown. Cane begins connecting the dots in his predicament and concludes a conspiracy theory: Marija and Isaac are his biological parents, and now Isaac is baiting him with money (and with Gwen) into rejoining the family. Devon, privy to his conspiracy theory, casts doubt on it. Cane, unsure of what to think but certainly distrustful of the "nasilnik" Isaac, decides to spend a day off tracking his movements and digging up whatever he can find. While doing this, he finds out that Rachel has decided, with no prior planning, to move to Colorado for grad school. This, too falls right into place for Cane's conspiracy theory--she must have been paid off to leave him alone. Cane meets Gwen for dinner that night, where she asks him to consider looking for an apartment together. Cane agrees to consider it; but, still not fully trusting of the whole thing, surreptitiously collects a DNA sample from her (and himself) to help prove or disprove his theory.
Cane, back at work, sleep deprived and utterly burnt out, gets sloppy at work. This further weighs on him, which brings him to the end of his rope with a pain in the ass coworker, Karl, whom he nearly starts a fight with in the dining room. The manager, Dom, breaks it up and interrogates Cane's behavior--Cane holds most of it back but excuses it with the revelation of his adoption. Dom, empathetic, gives Cane a reluctant night off. On his way out, Cane encounters Isaac and Martha on their way in--they decide to cancel their dinner plans, and Cane suggests home cooking at the penthouse.
While prepping for dinner, Cane attempts to subtly pry more information from Isaac about his relationship with Stipan and Marija. Isaac seems to pick up on this and pushes back a bit. Cane, a bit tense, readies himself to leave after dinner, especially now that Martin has arrived. Gwen texts him to stay there, as she's on her way back, but he still tries to leave--Isaac and Martin have gone downstairs to the shooting range and Martha has disappeared to somewhere else in the penthouse. Stipan and Marija are also nowhere to be found, which is inconvenient for Cane as he finds the elevators and exit stairwell locked. Just as the panic begins to set in, Gwen arrives, and he calms for a moment. This calm is quickly erased, as she reveals that she's pregnant. Completely dumbstruck, Cane collapses, falls down a marble staircase and cracks his head.
He awakens from a coma a week later in one of the penthouse guest rooms, hooked up to homecare medical equipment. Once again, the exit door is locked, and panic sets in again. Gwen again tries to calm him--standoffish, he demands that she terminate the pregnancy and she rebukes him, trying to convince him that they can begin a family together. He asks to see his phone and heads out to the balcony for some air. In his email inbox are the results of the DNA test he ordered on himself and Gwen. As he goes to open the email, he pauses to admire the view of the city from up there.