Reflections and parallels abound, as do divisions and refractions, in writer-director James Sweeney’s impressively confident and visually inventive Twinless, a film where mirrors — and identical twins — seem to pop up around every corner.

Any comedy is built around mayhem and uproar, and the rom-com genre homes in a specific subset of wildness: A deception becomes irremediable and then spins completely out of control. That’s what happens here, though Twinless isn’t exactly a rom-com; it’s a brom-com, if anything, and while the film’s general structure is familiar, its premise is so shocking that twenty minutes in you find yourself saying, “What the fuck!” Ten minutes after that, that exclamation transforms into: “This is fucked up!”

So it is, but Sweeney manages to keep his characters sympathetic even when they disgust or terrify us. He doesn’t go easy on the hapless, jumpy Dennis, whose needy loneliness runs the risk of starting to grate. Franciosi, as Marcie, is much more than the love interest who starts to come between the guys; she’s written, and played, as a sunny soul who finds the best in every situation but knows when and how to draw the line.

O’Brien is given the meatiest roles, plural. He does fine work as Roman, who is not particularly bright and whose sweetness is clouded by occasional violent outbursts. His talents stand out when he plays Rocky in a flashback — plays him so well that at first you might not recognize him as Roman’s twin. Where Roman is somewhat shy and slightly sullen, Rocky is outgoing, radiating confidence and sexual charm. But it’s in a long, almost unbroken monologue in which Roman is speaking to his dead brother — Dennis acting as a stand-in for Rocky — that he breaks your heart, then makes you laugh, then breaks your heart all over again, coruscating from grief to rage and then gutting despair. It’s a remarkably authentic moment in a movie filled with head-spinning lies. Credit to Sweeney, as well, for how it’s written and directed.

The film offers other cinematic pleasures, many of them visually stylistic. In one scene, a giant ceiling-mounted mirror looks down, duplicating and dividing below from above; a little later, a hall of mirrors serves as the setting for an only partially fabricated anxiety attack; and, in a startling tracking shot, the camera retreats backwards through mirror after mirror, as though gliding through a succession of doors, as Dennis records and re-records a bonkers voice mail greeting that, when we hear it earlier in the film, seems like a throwaway gag. “Caffeine does things to me,” Dennis confides early on, and we should be grateful that he avoids coffee because it doesn’t seem altogether unlikely that a cup of joe would cause him to split, like an amoeba, into dozens of tiny, out-of-control versions of himself, chaos agents fanning out in every direction to wreak havoc. The film itself pulls off just such a trick when an ordinary-looking shot suddenly splits in two, becoming a pair of points of view that track Roman and Dennis at what turns out to be a crucial juncture of the movie. Sweeney is paying homage to a master, here; Jean-Luc Godard did the same thing in his 2015 film “Goodbye to Language,” where the technique was even more confounding, given that the movie was released in 3D and each of the split images went to a different eye.

Thankfully, Sweeney doesn’t take things that far. Indeed, he makes sure that the havoc Dennis causes stays neatly contained, while the film’s comedy is balanced by its discipline. If anything, the movie is almost too well-ordered, and some scenes and recurring tropes skirt genre cliché. Sweeney doesn’t pull his punches, however (and neither, when it comes to it, does Roman), and because of that, the film’s momentum carries it past moments that would otherwise feel narratively rote. The effect is that “Twinless” feels singular: Something rooted in the familiar that rears up to astonish, knock the wind out of you, and, eventually, redeem.

Twinless is streaming now on major VOD platforms.