Anyone who follows the careers of Irish writers and directors has, over the last couple of decades, had what might be termed a Neil Jordan Moment. These are times as you watch one of his films when your jaw drops and your eyes bulge and the synapses in your brain go ‘ping’. The werewolves emerging from the diner’s mouths in The Company of Wolves, the atomic mushroom cloud exploding over a mountain lake in The Butcher Boy, the shock reveal in The Crying Game that made the whole world catch its breath.

His new film, Byzantium, has more than a few of these moments, arresting glimpses into a character’s psychology that could only have come from Jordan’s singular imagination. Here’s one: a waterfall transforming from a clear, cold torrent to a cascade of steaming blood. The red flow is the result of a new victim entering a magical place, a round stone cell perched on the side of a granite cliff on a remote Irish island. This is a place where vampires are born. One of those few undead, Clara (Gemma Arterton) was made here two hundred years ago by Ruthven (pronounced Riven and played by Jonny Lee Miller), a cruel British Army officer who condemned her to life in a brothel once he had his way with her. Having found an arcane map that led her to the cliff-side hut, Clara was reborn in blood. Later, she had a daughter, who was also initiated as a vampire. Now Clara and Eleanor (an especially ethereal Saoirse Ronan) pose as sisters, flitting around the tired seaside towns along the south coast of England in search of sanctuary, somewhere they can be safe from the secret, all-male society of vampires that have been hunting them for centuries.

When their latest lair is discovered by one of those men, Darvell (Sam Reilly), mother and daughter flee to the coastal town of Newhaven, the place they lived in as mortal beings before their transformation. There, Clara insinuates herself with the shy, awkward Noel (Daniel Mays), owner of a run-down boarding house which she plans to turn into a brothel while Eleanor, two hundred and sixteen and never been kissed, returns to school and starts a tentative relationship with local boy Frank (Caleb Landry Jones). When her teachers (played by Tom Hollander and Maria Doyle Kennedy) discover the truth behind a seemingly-fantastical writing assignment, they start to investigate these strange sisters and their sinister lives, laying a trail of clues for the women’s pursuers to follow.

Adapted from the play A Vampire Story by Moira Buffini (who co-wrote the screenplay with Jordan), Byzantium marks the director’s return to bloodsucking fiends twenty years on from his sumptuous, suffocating take on Anne Rice’s Interview with the Vampire. In the interim, vampires have become commonplace, from Buffy to Blade, True Blood to Twilight, with Jordan deliberately seeking out a new direction for his immortal characters, a steady accretion of tone that builds into a melancholy atmosphere of Gothic dread. Every vampire story has to re-write and re-establish the rules: Jordan’s monsters don’t have fangs, but draw blood through elongated thumbnails that stiffen and sharpen at the sight of a bare neck. They don’t seem to be affected by daylight, or garlic or crosses or running water, although they do require an invitation to enter people’s homes. They are also immortal, suspended in time, with Jordan cutting between the centuries to tell the story of how they came to be alongside the story of what they have become.

It’s an ambitious structure but the problems with Byzantium are in the story itself, not in how it is told. Clara and Eleanor’s twinned sagas aren’t dark enough to be horrific, subversive enough to be truly original or nuanced enough to be convincingly political. There is little sense of the vampire’s compulsion to feed, that predatory parapsychology that marks them out as fascinating, inhuman creatures driven by something we cannot understand. As characters, they are shallow and one-dimensional: Clara seems only motivated by money, using her flawless body to provide them with the resources to ensure their survival, while Eleanor’s self-imposed moral code only allows her to drink the blood of the elderly dying, who see her as a kindly angel of death in their last moments.

Later, the balance of power Jordan had spent time carefully establishing is seemingly abandoned to allow the threads of the story to better fit together. This jarring uncertainty is part of what marks the film out as an original work but are also what causes it to gradually lose its power to unnerve and disturb. The wandering plot lacks the heart-stopping lyricism of Jordan’s best work, but it does have its moments; startling visions we have never seen before that later, we cannot forget.