The Leftovers premiered in 2014 as an adaptation of Tom Perrotta’s novel of the same name created by Damon Lindelof (Lost) with Perrotta. The premise, as in the book, was that two percent of mankind suddenly vanished into thin air one October 14, in a Rapture-like event that left the remaining survivors grief-stricken and completely destabilized. All the institutions that people had put their faith in were suddenly rendered impotent and meaningless. And the brilliance of the show’s first season was that it wasn’t interested in what had actually happened so much as how the world might react to such an event. Cults suddenly sprang up all over the country based around charismatic healers and arbitrary principles, the largest of which seemed to be the Guilty Remnant, whose members wore white, smoked religiously, and strived to remind the world of the essential pointlessness of existence.

It was a premise explored with ingenuity and real psychological insight, but it was also often extremely bleak, which is possibly why some viewers departed themselves in the first season and never looked back. But the second, which aired in 2015, changed course. There were the new opening credits, a series of family photos set to Iris DeMent’s “Let the Mystery Be,” rather than the grave and imposing title sequence of season one, with its Renaissance-style frescoes depicting humans being pulled up to heaven. And there was the gallows humor that suddenly pervaded the show, particularly when it came to exploring how broken all its characters were. (The third season keeps this going: “I joined a cult, you know,” Laurie (Amy Brenneman) explains matter-of-factly in one episode, when someone asks her why she left her happy marriage. “Just one of those things they make you do.”)

Kevin (Theroux) and Nora (Carrie Coon) have always been the show’s MVPs, with Coon’s particularly sharp and vibrant performance as a woman completely unmoored by loss providing some of The Leftovers’ most heart-rending moments. But with Brenneman’s Laurie, Christopher Eccleston’s Job-like Matt, and Ann Dowd’s obliquely sinister Patti Levin, the show has one of the richest (and most perplexingly awards-free) ensemble casts on television, bolstered in season two by Regina King’s Erika, Kevin Carroll’s John, and Jasmin Savoy Brown’s Evie. Season three adds another virtuoso actor in Lindsay Duncan (Birdman, Sherlock), while also focusing more intently on Kevin’s father (Scott Glenn).

Season 2, Lindelof has said, was structured like a novel, with a beginning, a middle, and an end (like season one, which was based on a novel). But there’s a satisfying order to having, now, a final installment: Although the end of the second season functioned as a series finale, with (some) mysteries revealed and (some) families reunited, it was almost too tidy a conclusion. A last season that explores the prospect of a follow-up to the Great Departure puts yet more pressure on the show’s characters and the remaining people of the world, amplifying the themes of structural breakdown that The Leftovers has explored since the beginning.