In the world of “Shortbus” writer-director John Cameron Mitchell, “You’ve gotta get on to get off.”

Mitchell — who wrote, directed and starred in 2001’s cult hit musical “Hedwig and the Angry Inch” — manages the unlikely feat of fusing hard-core pornography with a compelling, emotionally-driven narrative. “Shortbus” is definitely the most sexually explicit film (that’s not actually porn) to come out of Hollywood. Mitchell has described his sophomore effort, in which humor and heartbreak are inextricably interwoven, as a film “about love and sex that doesn’t censor itself in any way.”

“Shortbus” opens in a peaceful, abstract, animated model of post-9/11 Manhattan, swooping through the cityscape and into three very different bedrooms, all to the jazzy, seductive crooning of Anita O’Day. First we meet James, a gay ex-hustler played by an introspective and wide-eyed Paul Dawson, struggling to contort himself into a self-fellatory (orally onanistic?) position. Next, we see Sophia (Sook-Yin Lee), the sex therapist who, ironically, has never had an orgasm, and her husband Rob (Raphael Barker) in the throes of a Kama Sutra marathon. Finally, we visit Severin (Lindsay Beamish), a dominatrix with an annoyingly wimpy client. The opening sequence climaxes with a clever ejaculatory joke made at the expense of a Jackson Pollock-esque painting.

For all the graphicness of the film’s first ten minutes, though, the sex in “Shortbus” is not intended to titillate or shock and rarely feels exploitative. Instead, the sex scenes are naturally integrated into the overall plot. Mitchell shows us sex that is often humorous and playful (notably, in a lighthearted menage a trois featuring a spirited rendition of “The Star Spangled Banner”), but at other times is frustrating or melancholic. His candor is undoubtedly intended to normalize sex in an increasingly prudish Hollywood and provides another way to understand the film’s emotionally-challenged characters.

Hoping to solve their sexual dilemmas, James and his long term partner Jamie (PJ DeBoy), Sophia and Severin all converge nightly at Shortbus, an underground club for “the gifted and challenged” where “voyeurism is participation.” Overseen by a mistress with a flair for outlandish makeup (drag diva Justin Bond, aka Kiki of NYC’s “Kiki & Herb”), Shortbus is a nexus of art, politics and polysexual carnality. Looking out over the orgy room, Justin says, “It’s just like the ‘60s, but with less hope.” And while the sexual frankness certainly recalls the swinging mentality of the 1960s “sexual revolution,” here it is tempered by four decades that have seen the rise of AIDS, the proliferation of Internet porn and an increasingly fervent return to puritanical morality.

James and Jamie have little trouble turning their duo into a trio, quickly hooking up with an adorable young model named Ceth (Jay Brannan), and Sophia and Severin strike up an unlikely friendship with the dual purpose of helping Sophia achieve the Big O and allowing Severin to “have, like, a real human interaction.” The film’s subplots are neatly interwoven and the frequent cross-cutting between parallel stories — which could easily have resulted in a fragmented film — is logical and cohesive.

Through the examination of the various characters’ sex lives, Mitchell seems to be asking the question: is sex — and good sex at that — necessary to achieve true intimacy with someone you love? And while “Shortbus” doesn’t deny that two sexually dysfunctional people can still have a loving relationship, in the end it seems the answer is yes. In a culture that seems bent on demonizing sex, “Shortbus” legitimizes its importance as a natural and healthy part of adult life. While the film’s explicitness might suggest a certain directorial carelessness, Mitchell is never disrespectful regarding the deeper implications of sexual intimacy. He has managed to escape both the vapidity of pornography and the immature, often cliched treatment of sex in mainstream cinema — the physicality of sex is treated casually, but its emotional aspects are never ignored or trivialized.

Mitchell’s portrait of New York is an idyllic one — one in which everyone is free to embrace their sexual otherness, and orgasms are described as a way of connecting to the greater web of human relationships. In the end — for anyone not too prudish to enjoy it — the film is an affirmation of the joyous and, at times, healing power of sex. Watching “Shortbus” is an experience that is both uplifting and optimistic: After all, voyeurism is participation.