(CNN) -- Mark (John Hawkes) is a 36-year-old virgin and impatient to do something about it. But he's also a good Catholic, which complicates matters. And then there's his domestic situation: he spends most of the day horizontal, in the iron lung, a cylinder that looks a bit like a torpedo tube, that helps him breathe. Since he was struck with polio as a child, Mark can't survive outside this apparatus for more than four hours at a time and even then requires a gurney to get about. He tries not to let it cramp his style, but this is not a lifestyle conducive to courtship and seduction.
We've seen films about severely disabled artists before (Daniel Day-Lewis picking up a paintbrush in "My Left Foot," Daniel Auteuil writing his autobiography a blink at a time in "The Diving Bell and the Butterfly") but rarely about their sex lives. Based on poet and journalist Mark O'Brien's memoir "The Surrogate," "The Sessions" has a different set of priorities. It's a given that Mark can write, but whether he can get it on with a woman, that's another question entirely, and a far more intriguing proposition.
A romantic crush on his caregiver comes to nothing, she doesn't love him "that way," but someone recommends professional help: a sex surrogate. Enter Cheryl (Helen Hunt), married, discreet, patient and practical enough to take a very nervous and over-excitable client through his paces over half a dozen assignations.
It's a cliché that actors playing disabled always win accolades, but these are also technically demanding roles, so why not? Hawkes, known for breakout roles in indie hits "Me and You and Everyone We Know," "Winter's Bone" and "Martha Marcy May Marlene," is terrific here: emaciated, bony, funny, his voice high-pitched and nasal, both confident in himself and oh so vulnerable.
It's good to see Hunt back too in what feels like her best movie role in a decade; she's forthright, tender and ultimately left high and dry by an unusually abrupt third act. Kudos to Moon Bloodgood and Ming Lo as well, for their deft comic underplaying as another of Mark's nurses and the motel receptionist curious to know the nature of this weekly therapy.
As are we, and this light but poignant crowd-pleaser of a movie doesn't disappoint on that score. Writer-director Ben Lewin, a veteran who has worked mostly (but intermittently) in TV, builds on the sexual candor pioneered largely by cable series and Judd Apatow-style comedies over the past decade or so.
Typically, that involves full-frontal nudity for Helen Hunt, but not for Hawkes. This conventional chauvinism aside, and adopting confessionals with Mark's long-haired priest (William H. Macy) as a comic safety valve, the film is refreshingly frank about the nuts and bolts of physical intercourse, as well as the more complex emotional exchange that is taking place.
What's the difference between a surrogate and a prostitute? Cheryl doesn't want the money upfront, and she doesn't want repeat business either (six sessions and that's it, she warns him). But what passes between them is too intimate, too personal to be strictly business, at least from where Mark is lying. Does Cheryl see it differently? Lewin suggests she too is touched by the experience; not by the sex itself, but rather the effect it has on Mark, and his ability to put it into words.
Is that just movie romanticism? Maybe so, but "The Sessions" is a very different kind of love story, breaking taboos lightly, with sensitivity and humor.