Last night’s Season 4 finale of The Americans raised some mighty big questions: In his feverish state, did William give up Philip and Elizabeth to Agent Beeman? Will Mischa, Philip’s son from a previous relationship, come to American to find his father? And will the Jennings’ even be there when he arrives? The finale dangles the possibility that the Jennings family is on the brink of a move to the motherland, a fittingly precarious ending to a season that’s seen the family at its most vulnerable. But it’s not just the focus on family that makes The Americans so humane despite the fact that it’s one of TV’s bleakest shows. The emphasis on conscience gives the series a heightened moral clarity, and Season 4 saw the spy characters more conflicted than ever about their work.

This season, Elizabeth grew genuinely attached to one of her agents, Young-Hee. Philip, who raised the idea of defecting to the United States back in the pilot episode, found a confidant in William, a fellow illegal who was reluctantly developing a deadly biochemical weapon for the KGB. There aren’t many two- or three-episode guest arcs on this show; newly introduced characters like Young-Hee and William tend to stick around for a season or more so we get used to them, get to know them and become attached to them like Philip and Elizabeth do. When they’re discarded — like Young-Hee, whose family Elizabeth tore apart to help William develop his weapon; Martha, who was forced to flee to Russia; or Nina, who was bluntly dispatched with a bullet to the head — we feel the human cost of even a cold war.

The Americans has always been a sorrowful show, but Season 4 reached new depths of despair. The characters’ ability to repress their natural instincts in the face of their brutal work begins to break down, and they’re left with the simple realization that they’re human. For William, that breakdown is both emotional and physical. In the finale, surrounded by FBI agents, William is forced to inflict his deadly weapon on himself — a viral strain so vicious he had hoped it would never be used on any human. “In a few days,” he says once Agents Beeman and Aderholt take him to the hospital, “everything inside me that matters will have oozed out through my orifices. I’m a dead man. It’s a very weird feeling.”

Meanwhile, after some initial resistance, Paige appears to be comfortably living the life of a spy, brusquely informing on Pastor Tim and his wife, Alice. Aping her mother’s terse, no-nonsense tone, she informs her that Alice gave birth: “Girl. Claire Louise. Pastor Tim left a message. I haven’t called back yet.” The situation has clearly brought Paige and Elizabeth together; we’ve never seen mother and daughter appear closer. Later, Paige makes a move on Matthew, although the show leaves it ambiguous as to whether she’s trying to manipulate Stan’s son or if she genuinely likes him. But she doesn’t know that with William in FBI custody, her whole family is in danger.

Through a window above a special containment unit, Beeman and Aderholt watch William deteriorate. “At a time like this,” Aderholt says through a microphone, “we can all just be human beings.” The set-up of the scene — Beeman and Aderholt watching from above like gods, the hum of the clunky medical equipment, the consistent “beep” in the background, the robotic tone of the FBI agents’ voices through the speaker system — ironically contradict Aderholt’s reassurance. To them, William isn’t a human being but an operative with valuable information.

As William dies, he reflects on a life spent in the service of the KGB. He describes how hard it is to live truly alone, unable to confide in anyone else: “The absence of closeness makes you dry inside.” “But still committed,” Beeman suggests. “It was the only thing I had left,” William replies. (Emmy alert: Give this show all of them, especially for the writing!)

But as he becomes more delirious, he begins to babble, and it’s clear that William’s commitment to his work isn’t nearly as powerful as his desire for meaningful relationships. Slowly, information starts to trickle out. He wishes he could have been “like them. Couple kids. American dream. You’d never suspect them. She’s pretty. He’s lucky.” Beeman and Aderholt exchange glances. The episode ends on an ambiguous note as Philip and Elizabeth contemplate leaving American forever — and we’re left wondering if William kept talking, and if Stan knows who is neighbors really are.

Over the course of four seasons, The Americans has set up a contrast between the coldly pragmatic Elizabeth and the softer, warmer Philip; between the harsh Soviet Union and the cushy United States; between love for a cause and love for a person. The intensity of Philip and Elizabeth’s bond throughout the series suggested that working together for a supposed greater good brought the two closer together. But between William’s deathbed confession and Paige’s newfound sense of purpose, “Persona Non Grata” suggests that it’s not the cause that gives meaning to their relationships; it’s the other way around.