"You expect us to believe in fairy tales?” It’s the most telling question posed in Neil Jordan’s winsome fable about an Irish fisherman who catches a pale young beauty in his net, and the answer is yes. Jordan, whose last fantasy, The Brave One (2007), was a sleazy celebration of vigilantism masquerading as something more, returns here asking us to suspend disbelief, and this time we’re happy to comply.

Jordan keeps one foot planted firmly in reality, but in Ondine there is magic as well. Syracuse (Colin Farrell) is incredulous that his soggy nets could capture such a striking creature, but there she lies before him, claiming no memory. She needs clothes and a bed, and Syracuse, who recognizes a gift when he sees one, selflessly volunteers his own.

His daughter Annie (Alison Barry), whose kidney ailment confines her to a wheelchair, thinks she knows where Syracuse’s unusual haul comes from. Annie believes in selkies – mythological sea nymphs of Irish and Scottish folklore, who take human form and settle briefly with landsmen – and suspects her father’s loveliest catch is one of them.

Calling herself Ondine, Syracuse’s secretive houseguest (Alicja Bachleda) does little to dispel the notion, and the fisherman, nicknamed “Circus” for his history of drunken buffoonery, wants to believe. Sober two-plus years, struggling to cope with Annie’s illness, Syracuse could use a run of good luck. If that requires him to suspend his own doubts, so be it.

That Jordan, who invites us into a seemingly magical world only to pull the rug out in the third act, chooses to give Ondine an all-too-real brush with her past – there’s nothing mythical about her, save for her perfect complexion – might have sunk Ondine. It doesn’t. Reality comes calling, and our illusions (along with Syracuse’s) are shattered. But there is magic still in the bond that binds Ondine to Syracuse, who sees her as something like a savior.

Several things work to elevate this slight but touching fantasy, the first being an engaging performance from Farrell, whose Hollywood misadventures might at one time have earned him the nickname Circus on his own, but who has resurrected his career with strong performances here and in Martin McDonagh’s quirky 2008 drama In Bruges.

In Ondine, he plays Syracuse with the world-weary charm of an actor who knows his character, perhaps a bit too well. Also impressive is Christopher Doyle’s handsome cinematography, which takes the photogenic Farrell and Bachleda (a real-life couple) and sets them against a rich backdrop of deep-sea blues and gray skies that are somehow less than foreboding.