Sea creatures, fairy tales, and Colin Farrell don’t seem a natural mix. Neil Jordan and unpretentious filmmaking aren’t exactly an expected pair, either. And so Ondine is a lovely, low-key surprise.

Farrell, still in serious-actor mode following his small roles in Crazy Heart and The Imaginarium of Doctor Parnassus, plays a greasy, working-class fisherman named Syracuse—but everyone calls him Circus, because he has a history of being little more than a drunken joke. He’s sober now but had to leave behind his wife and ailing daughter in order to ditch the sauce. So all he has at the beginning of the film is a shack and his boat on the Irish sea. (There’s not even a local AA chapter for support: for that, he visits his priest.)

Syracuse rarely catches anything, so it’s doubly surprising when he lifts his trawl one day and finds in it an unconscious, gorgeous woman (played by Farrell’s real-life squeeze, Alicja Bachleda). When she starts gulping air, they’re both surprised that she’s alive. She’s also confused and skittish, insisting that she doesn’t want to go to the hospital and, in fact, doesn’t want to be seen by anyone besides him… because he fished her out of the water, she says. It probably doesn’t hurt that he’s handsome.

The woman eventually calls herself Ondine—meaning “from the water”—and stays with Syracuse. She sings the next time she’s on his boat, a mournful, ethereal-sounding ballad in an unrecognizable language. (Jordan makes it even more exotic by echoing the audio.) And then Syracuse starts hauling in nearly more lobsters than his dinghy can hold. This turn of events, combined with Ondine’s question mark of a past, lends credence to the theory of Syracuse’s wise-beyond-her-years daughter, Annie (Alison Barry), that Ondine is actually a Selkie, a seal that can shed its skin and become human (and grant its host luck). In return for the booty, Syracuse buys (and steals) Ondine some nice clothes, including lingerie that she tends to bust out of. Unsurprisingly, the exchange leads to a quasi-romantic, unconventional-family thing.

The film is plainly invested in myths, wishes, and stories: Syracuse tells them to Annie and regularly asks her if anything “strange or wonderful” has happened. Annie often talks about Alice in Wonderland as well as the legend of Selkies. Still, Ondine goes over like a gentle breeze. It encompasses darkness too, both literally, with scenes shot in ink-black night or gray Irish days, and figuratively, with Annie’s mum (Dervla Kirwan) still drinking and her boyfriend (Emil Hostina) a fight-loving clod.

Annie also suffers, from kidney failure. But even as she must rely on a wheelchair, she, even more than Ondine, brings considerable light to the film. A smart, curious kid who doesn’t feel sorry for herself, Annie spends weekends “practicing my wheels” and insists her classmates are jealous. In turn, the adults in Annie’s life don’t condescend, and Ondine in particular forms an easy friendship with the girl.

Such emotional complexities don’t preclude comedy, most evident in the dry repartee shared by Syracuse and his priest (Stephen Rea) in the confessional booth. Their exchanges underline Ondine‘s sly, joyful combination of convention and inventiveness.