Danielle is a privileged professor, studying the deep, deep depths of the ocean. She spends Christmas at a swank hotel in France, where she meets James on the very cold beach, and they go for a swim. James is a hydraulic engineer who drills wells in third world countries. He dreams of Nigeria, but I’m not sure they’re always sweet dreams. They fall in love, of course. Danielle (Alicia Vikander) and James (James McAvoy) have a whirlwind hotel romance, but eventually they’ve both got to go back to work.

Danielle ends up on a deep-submergence vehicle where the tiniest mistake may mean death. But she’s seeing parts of the ocean that inspire her research and scratch her science itches. It’s too bad that she’s constantly distracted – James, you see, has been out of touch for weeks, then months. She doesn’t know whether he’s dead or just ghosting her. Unbeknownst to her, he’s been taken hostage in Somalia by jihadist terrorists, who suspect he is a British spy. He suffers months of torture all the while dreaming of their idyllic Christmas refuge.

Submergence is, therefore, two very separate movies, and its only strength is the chemistry between the two leads, which is very brief indeed. Once they’re isolated, they’re very isolated – he in a windowless cell, she in submarine miles underwater. It’s lonely and cold.

Here we have a salt water spa experience called Källa . In its 12% salinity, you float, weightless. The tomb is quiet, and pure. With little other sensory input, you are alone with your thoughts, which seem to float along the surface just like you. This movie is a little like that. It’s got no real weight, just snatches of remembrances and memories that paint a lovely flashback but that’s about it.

I suppose there’s a metaphor here – how love is a refuge in a violent world – but it’s just so darn inaccessible, and frankly, it tries one’s patience. And that’s really too bad because McAvoy and Vikander are doing gorgeous work that’s just gone wasted. Sad face.