After The Flood review: This new ITV crime drama has a knotty mystery at its centre, but ends up getting swamped

We've just seen widespread flooding across England thanks to Storm Henk, while a few days ago the UK Centre for Ecology and Hydrology announced that July to December last year was the wettest six months on record in the UK.

So it could almost seem a bit crass for one of our main terrestrial TV channels to start showing a drama series called After The Flood (ITV, Weds, 9pm).

However, the flooding itself is merely the Macguffin that gets our action going in what turns out to be a crime thriller centred around the discovery of a mysterious body in the lift of an underground car park.

The series starts with an action set-piece as pregnant police officer Jo (Sophie Rundle) tries to help a woman and her baby in a car stranded in the middle of the rising floodwaters. Before you can change “climate crisis”, the mum stumbles and the baby floats away on the raging torrent, the tot in a its car seat bobbing around like Moses on the Nile.

A mysterious man (Jonas Armstrong) leaps in to save the baby, managing to pass him on to Jo, who is waiting on the riverbank, waist-deep in water.

Jonas, however, is swept away. We know we'll see him again as this is Jonas Armstrong, who seems to have a contractual obligation to appear in every crime drama on TV these days – and sure enough, a little while later, we see him washed up on the banks, coughing up river water, before limping away in that suspicious manner he always carries with him.

That opening sequence is all a bit much however, even resorting the familiar action movie trope of dashing hopes before raising them again.

In this case, an empty car seat bobs up from beneath an inundated bridge – oh no, is the baby dead? No! Here comes Jonas, moments later, the baby safe in his arms.

Paradoxically, it's when the floodwaters recede and everything calms down a little that the real action starts.

The body is discovered, the clean-up begins and Jo has to struggle with the aftermath, her male chauvinist pig of a husband and his appalling family, who have come to live in their flood-free house on a hillside after being evacuated.

Meanwhile, Jo's mum Molly has become a climate change activist after their village has repeatedly fallen victim to floods and politicians of all levels have promised much and delivered little.

And Jo – seven months' pregnant, let's not forget – is just starting detective training and is desperate to stay on the car park body case.

There's a nicely knotty mystery here, as it's revealed the man didn't perish in the flood, but died some time earlier.

However, it's too often undone by massive exposition dumps and heavy-handed repetition – many times we're told that the flood sirens didn't work and politicians are useless, while the entire plot is summed up by Jo in just one breathless speech.

“How did the body end up in there?” she asks hubby Pat, who is also a police officer. “Who put it there, and where was it before and why move it and if he didn't drown, how did he die? I mean, it is a murder, isn't it?”

Meanwhile, Jo suggests to her mum that she should go into politics to change things, rather than whinging on the sidelines, but Molly seems to be unsure where to start.

A quick Google later and she has the answer. “I need to stand for election”, she says, in a revelation that surprises no one but her.

Pat is such a passive-aggressive horror that you wonder how Jo – who is clearly capable and driven – ever got together with him, while his family seems to be a caricature bunch of loudmouth, crass Northerners.

There are good bits here – the flood sequences at the start are impressively done, Rundle herself is an appealing heroine and the cast is great; we've barely even seen Philip Glenister yet.

And, like Jo, you want to know more about how the body ended up in the car park, and who he is.

Ultimately, After The Flood could still sweep you away, but it might end up swamped by its shortcomings.