If you don’t yet think that Blue Lights (BBC1) is on its way to becoming a new Line of Duty (but less far-fetched), by the end of this series you may have changed your mind.

You are about to be served up twists, rug-pullers, dodgy lawyers, shady police deals, heartbreak, domestic violence, murder, sexual abuse, childhood secrets, wit and dialogue that elevate it above the usual cop show. I am a fan, although I still don’t think the last series should have beaten Wolf Hall: the Mirror and the Light at the Baftas.

Episode one started pretty mundanely: cosy couple Stevie (Martin McCann) and Grace (Siân Brooke) in their patrol car discussing Stevie’s boring buns (again). He is such a Bake Off-type obsessive, he had ordered cocoa powder from a chocolatier in Belgium. How come he and Grace are always stuffing their faces from his Tupperware box yet both are as thin as a whippet?

Anyway, the cake break didn’t stop them from arresting a young street drug dealer, Sandy, and thus compromising an intelligence surveillance operation. They didn’t know he was being secretly tailed to lead detectives to an encrypted app that gangsters are using to sell high-purity cocaine. Blue Lights’ strength has always been to start small, showing how tiny incidents are a portal to a much bigger picture.

This series will take us away from the usual street grit and into the world of privileged, middle-class cocaine use, specifically in a new swanky private members’ club in Belfast run by flinty Dana (Cathy Tyson), who is happy for moneyed professionals to snort away providing they are discreet and the ambience of her club remains “elite luxury safe space”. Fast forward to the wealthy local accountant George filling his hooter and then collapsing on the shag pile as the pianist tinkles away at a terrible version of The Whole of the Moon.

• Move over, Line of Duty — why Blue Lights is our best crime drama

Dana is furious with Donal Fogerty (Charlie Maher), the gang master dealer (who reminds me slightly of the comedian John Bishop), and tells him: “Tonight your world walked into mine and shat itself on the carpet.” Not literally, I hope. It looked pricey. While George was lying unconscious in hospital PC Shane Bradley used the patient’s finger to open his phone, something which we can safely file under “naughtypoos”. But he does class George as a “Rich south Belfast entitled wanker”. Surely this needs an acronym: RSBEW?

The most harrowing parts of episode one, in a series that can switch from whimsy to savagery on a sixpence, both involved violent death. When Annie and Aisling were called to a car crash in which a young man, horribly injured, was dying, it was a perfect example of the random horror to which emergency responders are subjected daily and expected to cope with.

The effect on Aisling (Dearbháile McKinney), who said prayers with him and put blood-stained rosary beads in his hands as his life ebbed away, then had to tell his parents, was harrowing.

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This series will show how beat police somehow mop up all the loose awfulness of life — mental health problems, drug abuse, a neglected baby shoved alone in a bedroom during a deafening, drug-addled house rave — as if it was nothing. And also witness cold-blooded gang murder as seen in the final moments when that young man’s body hit the tarmac and nearly Grace and Stevie’s car bonnet.

Blue Lights addresses the compromises the police have to make, with intelligence officer Paul Collins (Michael Smiley) later making a very controversial one. What I have always liked about Declan Lawn and Adam Patterson’s writing is that the dialogue is sharp, never clichéd. The lives of the officers feel real. Yes, it starts slowly, but this long-form storytelling is always worth the investment.
★★★★☆

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