The narrator of my meditation app (I realise I have lost about 98 per cent of you in those six word) spends 10 minutes a day bathing me in peace, soothing my soul, gently encouraging me to create calm from chaos: I do not think Ambient Andy would like Line of Duty one bit.

Eastern Daily Press: WARNING: Embargoed for publication until 00:00:01 on 12/03/2017 - Programme Name: Line of Duty - Series 4 - TX: n/a - Episode: n/a (No. n/a) - Picture Shows: Series Iconic **EMBARGOED UNTIL SUNDAY 12TH MARCH 2017** Detective Chief Inspector Roz Huntley (THANDIE NEWTON), Detective Sergeant Steve Arnott (MARTIN COMPSTON), Superintendent Ted Hastings (ADRIAN DUNBAR), Detective Sergeant Kate Fleming (VICKY McCLURE) - (C) World Productions - Photographer: Des Willie/ Aidan MonaghanWARNING: Embargoed for publication until 00:00:01 on 12/03/2017 - Programme Name: Line of Duty - Series 4 - TX: n/a - Episode: n/a (No. n/a) - Picture Shows: Series Iconic **EMBARGOED UNTIL SUNDAY 12TH MARCH 2017** Detective Chief Inspector Roz Huntley (THANDIE NEWTON), Detective Sergeant Steve Arnott (MARTIN COMPSTON), Superintendent Ted Hastings (ADRIAN DUNBAR), Detective Sergeant Kate Fleming (VICKY McCLURE) - (C) World Productions - Photographer: Des Willie/ Aidan Monaghan (Image: WARNING: Use of this copyright image is subject to the terms of use of BBC Pictures' Digital Picture Service (BBC Pictures) a...)

A year of mindful meditation was pretty much erased in the first 60 seconds of this fourth series of the thriller that pits AC-12 against bent coppers - my heart practically hammered its way through my ribcage watching a woman being struck by a car, bundled in to it and kidnapped by a balaclava-wearing nut-job who had a cavalier attitude to being spotted by witnesses.

She tried to escape, managing to throw herself out of the car and back on to the road, only to be scooped up by the driver and forced into the boot. No amount of breathing exercises on all the apps in the world could have stopped me practically hyperventilating.

There are plenty of witnesses to the hit-and-kidnap, so the boys and girls in blue are on the trail of the chap whatdunnit within minutes and before you know it, there's the woman – chained to a radiator in a house belonging to a convicted sex offender with no alibi. Bingo.

Thandie Newton is this season's big name and viewers were primed for her to appear for a matter of minutes before she met an untimely end (writer and director Jed Mercurio has a habit of killing his stars – Gina McKee was put on ice, Jessica Raine took a dive and Daniel Mays got it in the neck). Suffice it to say, I don't think anyone could have predicted what Mercurio had in store for Thandie, not that we're quite sure ourselves, yet.

Newton plays DCI Roz Huntley, who is worlds apart from the usual 'female cop balancing home life with work' caricature – when she answers a call to attend an incident, she leaves her teenagers at home, pausing briefly to call their father to tell him he's in charge and could he also remember to put out the bins.

She's been investigating a string of abductions and murders and is convinced of Michael Farmer's guilt. Or if she's not convinced, she's convincing, at the very least – to everyone other than forensic coordinator Tim Ifeld, brilliantly played by Jason Watkins, who alerts her to several anomalies in the investigative procedure (which she ignores).

We were a quarter of the way through the episode before the Holy Trinity of Superintendent Hastings (Adrian Dunbar) and Detective Sergeants Steve Arnott and Kate Fleming (Martin Compston and Vicky McClure), also known as AC-12, were called in to investigate Ifeld's claims.

Despite winning a high-profile award for her undercover work, Kate is undercover again and hoping no one has access to Google images. She tells Huntley that she's investigating a case from another police force and needs to interview Farmer.

There were shades of Making a Murderer about the interview scenes in which Farmer appeared to be trying to please the police with his answers rather than answering questions honestly – and then there was the might-as-well-have-not-been-there duty solicitor who was asleep during his client's questioning. It seemed unlikely Farmer could be a master criminal.

Twitchy and clearly furious she was under suspicion, Huntley decided to take matters into her own hands and visit Ifeld at home: it didn't go well.

The pair rowed furiously with each other and then all hell broke loose – there was a slap, retaliation, a burn, a tussle and before you knew it Tim was down at the local DIY store stocking up on all the essentials you need to dissect a corpse in your kitchen: rolls of plastic sheeting, portable chainsaw, bin bags…I hope he took his loyalty card.

We are being led down a path that suggests Ifield is, in fact, the kidnapper and ergo the murderer, but if this is the case, why would he be drawing so much attention to the fact that there are 'forensic concerns' about Farmer? Why wouldn't he just keep calm and carry on killing?

But anyway, back in Ifeld's kitchen, there was work to be done. As a frenetic eight minutes came to an end and we entered the last 30 seconds of Line of Duty, there was another curveball coming (and if you've got this far through the review and not realised it's strewn with spoilers - as are all reviews, it's their nature - then an almighty one is coming up).

Somehow, meticulous forensics expert Tim failed to notice the woman he was about to repackage was actually still alive. The very last shot was Huntley opening her eyes as the saw hovered an inch or two above her skull – it was a jaw-dropping conclusion to a fantastic return of this taut thriller that hasn't unduly suffered from its transplant from BBC2.

Is it too late for Huntley to save herself? Will Mercurio REALLY kill another big star in the first episode? Is the twist that it's actually Jason Watkins who is the big star? Can my recently-readjusted nerves cope with episode two? Will Andy-on-my-app forgive me for not having a 'mindful' reaction to Line of Duty?

* Line of Duty is on Sundays at 9pm on BBC1.