Bill Hader has one of the best, most malleable faces that’s ever been on television. As seen in his dozens of characters on Saturday Night Live, Documentary Now!, and beyond, his grins stretch the entire width of his face as his eyebrows strain to break the ceiling of his forehead. Meanwhile, the eyes in between are capable of widening in pure glee or narrowing into a coy, sinister glower, depending on what’s asked of them.

In Barry — the pitch-black comedy he co-created with Silicon Valley showrunner Alec Berg — Hader challenges himself to use all these skills and then some. And as Barry, a veteran turned hitman resigned to a life of murder and drudgery, Hader gets to flex not just his facial muscles, but his acting, writing, and directing ones, too.

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When Barry’s latest hit brings him to Los Angeles, he accidentally stumbles into an acting class (taught by a perfectly grandiose Henry Winkler) that pushes him to do something he hasn’t in a long time: be human. Forced to confront his own feelings — which he tried to turn off to do his job — Barry slowly but surely frays so much at the edges that it’s only a matter of time before he splits apart.

Barry is not, in other words, what you might expect of a collaboration between Hader and Berg. Throughout its eight episodes, the show gets bleaker and bleaker, twisting its comedy into something so dark it eventually envelops the entire thing. It doesn’t always work, but when it does, it’s hard to avert your eyes from its curious, unblinking stare.

Despite its premise, Barry is pretty funny!

Okay, granted, that’s a pretty dire description for a show that still finds a lot to laugh about.

Watching Gene Cousineau (Winkler) try to teach Barry how to act when the concept of emoting might as well be a foreign language to him is always hilarious, particularly when Winkler leans into Gene’s utter obliviousness. As Barry’s classmates, D’Arcy Carden and Darrell Britt-Gibson steal every scene they’re in, sometimes through just a single line reading.

As ambitious aspiring actress Sally, Sarah Goldberg has an undeniable sparkling energy that makes it easy to see why Sally captures Barry’s attention and imagination, as we see in sporadic cutaways to his perfect married fantasy life. But over time, Sally also reveals herself to be self-centered and impatient in ways both understandable and startling, and Goldberg finds a way to straddle the line every time.

Barry’s secret life also features a revolving door of hyperviolent weirdos whose casual approaches to their horrific jobs contrast starkly with Barry’s increasingly uneasy frustration. Stephen Root and Glenn Fleshler get the most material as Barry’s agent and a Chechnyan mob boss, respectively. But the clear standout after eight episodes is Anthony Carrigan as NoHo Hank, a Chechnyan flunky whose approach to crime is to politely ensure that everyone involved is comfortable and has enough babka with an earnest expression better suited to a puppy than a professional criminal.

And yes, of course, Hader finds moments in between Barry’s bouts of malaise to drive home exactly how ridiculous his entire situation is. But Barry’s somewhat surprising strength is in the moments when neither Hader nor the show backs away from exactly how awful his situation is — and the very real consequences of living a life in service of ending others.

But also, whew, Barry is dark

Despite Barry’s wacky attempts to be an actor — all of which are funnier for how clumsy Hader lets them be — Barry is an intrinsically tragic character. He’s a lost, depressed veteran who found a calling in the murder-for-hire business, a life he’s uncomfortable with but has no idea how to leave behind. Whenever he tried to insist he’s “done, starting now,” someone will inevitably find a way to pull him right back in.

Barry’s been so entangled in this mess for so long that he clings to the scraps of normalcy the acting class provides like they’re lifelines — and almost all of them backfire. He’s floored by the fact that Facebook can connect him to an old Marine friend, but quickly finds himself overwhelmed when they meet up and connect with some other veterans who have not exactly readjusted to civilian life. In another less significant but telling example, when Barry gets invited to a party, he doesn’t know what to wear and just buys an entire outfit off a J Crew mannequin.

As Barry tries to figure out how to be a person, Detective Moss (a wonderful Paula Newsome) tries to allow herself to be one. Her arc becomes one of the show’s best and most surprising, especially as she crosses paths with Gene and homes in on Barry. She and Barry are in a game of cat and mouse, alternating roles depending on the episode, and that tension keeps the show moving along at a brisk — and often very stressful — clip.

Even over just eight episodes, the show’s tone goes through several rapid transitions that don’t always land. By the end, however, Barry establishes itself as a uniquely empathetic shot of weirdness that hits its target more often than not.

Barry premieres Sunday, March 25, at 10:30 pm ET on HBO.