Racing into its second episode, BBC One’s Bodyguard fails to relent on the high stakes and terrific acting, as the terror level in the UK hits a staggering high.

After the excruciatingly tense opening episode of Bodyguard, you really wouldn’t begrudge writer Jed Mercurio the chance to decompress. David Budd has been through the wringer enough but – of course – he’s not allowed any chance to breathe before events kick into gear again.

Mercurio has no sympathy for Budd and by the end of the series’ halfway point, he’s almost had his kids blown up, his boss and lover assassinated, and just witnessed an old army colleague shoot himself. For a man with an already tenuous hold on his sanity, this doesn’t exactly bode well, and it’s indicative of Bodyguard’s complete unabashed commitment to testing its audience’s nerves.

We are literally barely five minutes into the episode and already there’s the very real possibility that we could be about to witness a playground full of kids get run over. Where Line of Duty was all about the slow burn and miasma of corruption in the police force, Bodyguard has its foot on the accelerator at all moments. It’s utterly gripping stuff.

In my notes for this episode I remarked that this episode had lost a smidgen of steam after the aggressively taut opener. I was halfway through writing that sentence when poor Terry the driver had his brains blown out, and Julia Montague’s lovely white suit – a neat choice by the costume department – was spattered red.

The attack on the Home Secretary came at the best possible moment. Mercurio visibly worked overtime here to dial Montague back from arch-villain territory. Where Julia was frosty in episode one, here she was a hard-working, kind, competent human being – and Keeley Hawes’ exquisite performance keeps her grounded in reality. Hawes is a great choice for the role because it’s impossible not to sympathise with Julia despite everything she’s done.

Seeing an immediate attack on her life raised the bar for how high stakes Bodyguard is willing to go. The double sucker punch of the sniper being one of David’s old colleagues was almost too much to bear, even if, when you think about it, it’s a tad silly. Nonetheless Jed Mercurio is doing a great job showing just how perilous a place this vision of the UK is.

Loyalty is proving to be something of a through line for Bodyguard, and by the end of this week’s episode we have no idea where current allegiances lie. David is being urged to illegally spy on his boss whom he obeys because she’s the Home Secretary and his lover, and he also doesn’t want to act in defiance of the law, whilst still wanting to entertain the very real possibility Julia Montague is a threat.

David has been placed in a thorny position and how he’ll come out of it is anyone’s guess. There’s little knowing where Mercurio could take the series but if Bodyguard is anything like his other works, next week’s episode will surely continue to pull the rug out from under us and have us reeling.

The most unexpected but not unwelcome twist in Julia and David’s story is their decision to couple up. In reality, an affair between the Home Secretary and her bodyguard would be the scandal to end all scandals, but here there’s barely any time to take in how outrageous a development it is.

Director Thomas Vincent and Jed Mercurio have unexpected form in showing such steamy scenes; Vincent was behind the camera for a few episodes of the BBC’s fairly blue Versailles, and Mercurio wrote Richard Madden and Holliday Grainger together in Lady Chatterley’s Lover. It’s a tonal deviation from what’s come before but it’s sensitively done, it lessens the unbearably tense atmosphere and for all their flaws, David and Julia deserve this moment of respite.

With the way things are going, we could all use some respite – but this is Jed Mercurio, after all. We’re going to go through hell and back again next week.

Bodyguard continues next Sunday on BBC One at 9pm.