Late in an early episode of Castle Rock, the show chooses a humorless moment to poke a little fun at the audience. Henry Deaver (Andre Holland) sits in halting conversation with a mysterious young man (Bill Skarsgård), their bodies separated by glass and their voices joined by jailhouse phones. Or Deaver's voice, at least—the young man opposite him has whispered only a few words since first being freed from captivity underneath Shawshank Prison, and is utterly silent now. Deaver, an attorney, outlines what he imagines their legal strategy to be; "You understand?" he finishes.

For a beat, the young man stares at him, all eyes and hair and cheekbones. Then speaks, his voice creaking with disuse: "Has it begun?"

One question, three meanings. For Deaver, it’s literal. For the viewer, who has by now heard and seen some … things about the young man, it takes on an unsettling gleam of ominous prophecy. But for the writers of Castle Rock, who have created a Hulu original series by essentially feeding Stephen King's literary catalog into a neural network, it’s a winking acknowledgment that preamble is done. After three episodes of scene-setting, of lore-building and creep-crafting, they’re saying, shit is about to pop off.

There’s yet another meaning to the question, though—one that only comes into focus if you take a big step back from the TV. Because the young man's question isn't simply applicable to Castle Rock, the first three episodes of which become available today. It’s applicable to a bigger movement within TV at large, and streaming services specifically. Netflix's pronounced push into science fiction with shows like Black Mirror and Altered Carbon has resulted in a now-common sight: its competitors following suit. Castle Rock, it seems, is only the first King-sized salvo, and over the next year or so it'll be followed by an unprecedented parade of genre fare from Hulu, Amazon, and YouTube.

Genre television is not a new idea for streaming platforms. One of Amazon's first forays into hourlong drama was an adaptation of Philip K. Dick's novel The Man in the High Castle, and The Handmaid’s Tale helped make Hulu a prestige player. (Even before that, Hulu had made its way into original series with shows like supernatural comedy Deadbeat.) But genre—and especially sci-fi—has proven to be specially suited to streaming audiences. It's story-driven; it's often pulpy, with that pulp stringing viewers from one episode to the next; it's less prone to I Have Important Insights About the Human Condition-style navel-gazing that can infect showrunners and bog down shows. And last week’s Comic-Con International proved the perfect opportunity for streaming services to tease their efforts.

Hulu threw all its might behind Castle Rock, and for good reason: while the service is reportedly developing numerous genre series, including ones based on Anne Rice's Vampire Chronicles and the comic book Postal, the Stephen King-inspired series is a) done and b) judging from the first four episodes, at least, good. The fictional Maine town it's named after is well-known to King fans (it serves as backdrop for Cujo, Needful Things, and novella "The Body," among others), and here it's given flesh, albeit desiccated flesh, as a blighted depression town with little to offer beyond opioid addiction and secrets. Deaver, a Castle Rock native, has returned after years away, only to discover that its denizens—from childhood friend Molly Strand (Melanie Lynskey, carrying a fine-tuned fragility) to the recently deceased prison warden (Terry O'Quinn) to Skarsgård's gaunt, feral mystery prisoner—carry secrets of their own.

Netflix's push into sci-fi has resulted in a now-common sight: its competitors following suit. Castle Rock, it seems, is only the first King-sized salvo, and over the next year or so it'll be followed by an unprecedented parade of genre fare from Hulu, Amazon, and YouTube.

As Deaver, Holland exudes a weary impatience that provides perfect counterweight to the macabre weirdness of the surroundings, especially as that weirdness takes on context. Despite having J.J. Abrams as executive producer, this is not a show of mystery boxes. There are boxes in Castle Rock, yes, but they're opened almost immediately, even if not everything inside is illuminated. "Stephen King doesn't really write mystery box novels," said co-creator Sam Shaw at the show's Comic-Con panel. "We tried to chart a course that in some ways is driven by some mysteries … and then also to answer some questions, perhaps earlier than the audience expects."