Mythology is filled with beings that are part-man, part-beast, or which change from one to other. There is a whole subgenre of these that are connected with water: mermaids, sirens, lorelei, water sprites and so on.

Mermaids are of course the best known and have inspired the most films. But the much more obscure creature from Scots seafaring folklore called a selky or selkie - a creature that changes from seal to (beautiful) human being and back -- has inspired two. The first was John Sayles The Secret of Roan Innish; the second is Neil Jordan's Ondine.

Both films relocate their alleged selkies to Ireland. This is perhaps not surprising given that Hollywood types still see rural Ireland as a place in which magic and mysticism is believable, while Scotland, at least since Trainspotting, has a rather less romantic image.

Jordan's experiment with the selkie myth features a female one, played by Polish newcomer Alicja Bacleda, and she is appropriately gorgeous even when lying unconscious in a trawler net belonging to fisherman Syracuse (Colin Farrell). She is even more so in the later scenes that have her going for a swim clad only in a clingy, transparent dress, or trying on underwear.

These are only some of the striking visual pleasures of this odd, slight film by the director of The Crying Game, Interview with a Vampire, and Michael Collins. He and his cinematographer, the justly celebrated Christopher Doyle (In the Mood for Love) make the most of the rugged coastline and overcast skies of Castletownbere, a village in County Cork in which Jordan has a home.

The girl in the net speaks simple English with a strange accent. She tells Syracuse that she had drowned but has come back to life. Though suffering from amnesia she asks her saviour to call her Ondine. (As fans of the ballet of the same name may recall, an undine in European folklore is a water nymph). She also begs him to keep her arrival a secet.

Syracuse responds with remarkable calmness and kindness. He is a loner and a recovering alcoholic who has been sober since his brilliant 10-year- old daughter Annie (Alison Barry) was diagnosed with kidney failure two years ago. (The people of the town call him "Circus" because he was such a clown when drunk.)

The wheelchair-bound little girl lives with her hard-drinking mother (Dervla Kirwa) and the mother's Scots boyfriend, and Syracuse comes by three times a week to take her to dialysis.

Obeying Ondine's to keep her presence quiet, Syracuse puts her up in his late mother's remote house and brings her food and clothes. When one day he takes her out on his boat, she sings a strange song and to his shock his lobster pots are full and his nets come up packed with fish that are almost never found on this coast. Eventually, inevitably but with so little fanfare that it almost undermines suspension of disbelief, they end up in bed.

Unable to keep Ondine a complete secret he tells his daughter about her but in the form of a fairy tale. (He also spills the beans to the sardonic local priest, played by Neil Jordan regular Stephen Rea, but in the safety of the confessional.)

Annie quickly figures out that the girl is not a figment of her dad's imagination and also half-persuades her father that the girl is indeed a selkie. After all, she has brought him amazing luck. According to folklore, as Annie finds out in the library, a selkie can take a landsman as a husband but only if she has no sea-husband. And if she has a sea-husband then he will come looking for her to take her back to the sea.

A sinister-looking man wearing black with a similarly odd accent does indeed turn up in town looking for a castaway. It is clear that things are going to get nasty and violent whether or not Ondine is really a supernatural creature.

Farrell is always good at playing moody, tormented men and he seems very relaxed playing one of his own countrymen again. Alison Barry on the other hand is given lines that no child actor could carry off without sounding irritating - Jordan has written her as one of those supernaturally precocious and intelligent Hollywood kids who have a lot to teach their parents.

Unfortunately Ondine has bigger problems. It is a strangely uninvolving and self-conscious film given its mythic source and potentially powerful storyline. Almost everything about it (except perhaps the lovingly shot scenes of Ms Bacleda) is so low key that it almost flirts with tedium.

Worse still, the fantasy mixes uneasily and unconvincingly with the realism, almost as if Jordan could not make up his mind about the kind of film he was making. The result is the kind of detached experience that prompts you to notice things like the fact that everyone in the film apparently comes from a culture in which shampoo is unknown, but has access to gorgeous jumpers, like fishermen in TV commercials.