Christian Petzold’s Undine is an intriguing, bemusing oddity of a film: a suspense drama-thriller with a fey supernatural twist. It’s a sphinx that, if not exactly without a secret, has less of a secret than it thinks it has. And it is possible to come away from the film less than convinced, but very impressed by the sheer force of Petzold’s film-making talent (recently so stunning in his drama Transit) but which has been here deployed for something which is a bit flimsy and silly.

Paula Beer plays Undine who, as her name suggests, may have intense sympathies with water. She lives in Berlin, and is a stylish and elegant historian who lectures on the city’s architectural history at the Berlin City Models exhibition. But she is also conducting an unhappy adulterous affair with Johannes (Jacob Matschenz), which is reaching its unhappy end at the film’s opening - revealing a flash of something angry and even violent in Undine.

But in the midst of this traumatic episode, Undine is to have a fateful encounter with a strange man who has heard her lecture, and appears to be in love with her. This is Christoph, an underwater diver played by Franz Rogowski - a sensual screen presence with a little of Joaquin Phoenix. Soon Undine and Christoph are having a passionate affair, and he introduces her to his mysterious professional world, little guessing that she may be far more at home in it than he ever could be.

Their relationship is passionately sensual, though Undine is perplexed at the sheer rapture with which Christoph listens to her lectures about Berlin’s planning history. Is there a metaphorical dimension to this? Maybe. Certainly their emotional connection has restored something like happiness to her, and effaced the mad furious unhappiness of her former liaison. But then she is to chance across Johannes once again and a terrible destiny begins to stir in those watery depths with which Undine feels such empathy.

In truth, Undine is a bit of a shaggy dog story, or maybe a slimy giant catfish story; though it is just so skilfully made, beautifully acted and directed. Rogowski brings something unstable and dangerous to the part and so, in a more contained way, does Beer. What might this cast and this director do if they were working on a more compelling and substantial story? As it stands, Undine is a diverting and handsomely crafted piece of fantasy.

• Released on 2 April on Curzon Home Cinema