Marcella the TV show - like Marcella the character - is complicated and confusing but occasionally there are flashes of brilliance. Who is scarier: the baddies or Marcella? The jury is out.

Normally, if you were under attack, in danger or in fear for your life you'd be grateful to see a member of her Majesty's police force arrive.

If, however, the police officer in question was Marcella Backland, you might think twice or, indeed, she might be the one attacking you, putting your life in danger or embarrassing you in front of an entire school yard full of your peers. Ah, Marcella: we've missed you.

Marcella (a wild-eyed and frenetic Anna Friel) picks up a few months from where we left series one with our heroine teetering on the edge: quite literally as it happens, because she's dangling off the roof of the building where she works, in comparison to metaphorically, which she appears to be at all times.

Flashing back 12 days, we're in a lovely Georgian house under the shadow of a tower block in London where building work is going on: as excuses go, 'I've found an ear in your wall cavity' is one of the more believable ones you might be offered if your renovation project was delayed.

The ear is strangely preserved even though the body it's attached to isn't – despite this fact, Marcella recognises the body as Leo Priestly, the missing friend of her son Edward, who disappeared in 2014 and whose parents blame Marcella and Edward for his abduction. Surely this would mean Marcella wouldn't be allowed to work on the case? Don't be so ridiculous.

But back to Marcella, who remains as miserable as ever: the only time she cracked a smile was when she cracked open a beer shortly before viewers saw her post-coitus bum cr… no, we'll leave it there and crack on. Six months on and Marcella has somehow retained her job and is working on the Priestly case with DI Ronnie Ferreira from EastEnders (Ray Panthaki), DC Mark Travis (Jack Doolan), her new love interest and boss DCI Tim Williamson (Jamie Bamber) and newcomer LeAnn Hunter (Sophia Brown).

In other news, her estranged husband Jason (Nicholas Pinnok) hasn't let the grass grow under his feet and is about to marry a woman half his age who Marcella accepted into the family fold by dragging her out of her car, throwing her across the bonnet and attacking in front of her son's school. I'm not convinced she's over Jason.

Oh, and the parka has disappeared, only to be replaced by a hugely impractical trench coat with Harry Hill-esque lapels which are so large they practically drag on the ground, partially impeding her ability to attack love rivals and wander around crime scenes alone at night: RIP Parka.

As is the case with these Brit-Noir mysteries, there are a whole lot of threads that currently make no sense whatsoever – Nigel Planer plays 70s rocker Reg Reynolds, who lived in the flat from which the dead boy's final resting place was accessed, there's an angry skinhead called Eric who approached a man called Nick who in turn has a son called Simon who Eric has been watching. Simon has a friend called Adam whose mum married Fat Barry in EastEnders and who drew a picture of a schoolboy killing a man while in detention.

I don't think it was Fat Barry.

And most disturbing of all, we saw flashbacks to Leo's imprisonment in a derelict house, the chained teenager desperately scraping at the wall as his captor(s) menacingly approached and later strapped him to a gurney, kept one of his eyes pinned open and then stroked a few surgical tools before injecting the terrified boy with a drug.

There was then a post-mortem macabre Victorian-style photo shoot featuring the lifeless boy posed in a chair wearing a suit: back in Queen Vic's day, no one thought twice about posing the dead for a lovely family snap, these days, I believe it may be frowned upon, definitely if you then sandwich them in your wall. Anyway: Happy Monday! Talk about bleak.

As for Marcella, she makes Luther look placid: she stalks weirdly across the screen ('as if she has a broom up her backside,' my husband said, nailing it) and is prone to fugues – a dissociative disorder, not the American hip-hop band which is a different spelling – during which she effectively blacks-out while she creates mayhem, a bit like Mr Hyde but without Dr Jeckyll. We discovered at the end of the episode that someone is watching her through her computer via a webcam: I doubt whoever it is will get a happy ending.

One thing that Marcella is not is subtle. Viewers are clubbed over the head with imagery – when the paedophiles are on screen everything goes dark, when bad things happen the music turns up the Hammer Horror volume to 11, when we meet the exploitative owner of the firm that Eric works for he might as well be wearing a cape and twirling a moustache, we learn that Marcella 'isn't well' mainly via the fact that she doesn't brush her hair. A lot of the time, this show is a bewildering mess with a soundtrack which is almost unbearable.

The rest of the time it's brilliant. A bit like Marcella herself, really.

* Marcella continues on ITV on Mondays at 9pm.