Was the jittery lady in the railway carriage loo about to activate the device strapped around her chest, blowing all on board to kingdom come?
As her thumb hovered over that button, it was hard not to fear the worst.
Which was daft, really.
We must have known she wouldn’t do it, this being the very first scene of asix-part series, where the guy standing in front of her, calmly trying to talk her out of it, was the person the whole show’s named after, ex-Army chap David Budd (Richard Madden).
Now working as a cop in a protecting-important-people role, he’s about to be assigned the task of stopping people killing the Home Secretary (Keeley Hawes’ character, Julia Montague).
But even so, it still made fabulously nerve-shredding viewing.
So what’s David up to tonight? Well, the key points we’ve learnt so far are: (a) the Home Secretary is determined to introduce a set of controversial new counter-terrorism measures; (b) bodyguard David doesn’t much care for the Home Secretary’s politics, nor for the fact that she treats him like something rather unpleasant she’s just trodden in; (c) David has other ex-Army pals who like her even less; (d) David is a lot more hot-headed than his on-duty persona implies; and (e) David’s got a gun. So he might just go ahead and shoot her tonight in the first five minutes, that’s the implication and free up the remaining 55 minutes’ airtime for, say, a repeat of DIY SOS.
But (spoiler alert) he doesn’t do that.
I mustn’t reveal exactly what he does do but there are three thumpingly significant scenes in this second episode, each with a colossal impact on the plot and on the dynamic between this pair.
We soon realise this is going to be a lot more tangled and complex than episode one has suggested.
And, as with Line Of Duty, the underlying message will be: trust nobody. Ever.
Elsewhere tonight, speed with GUY MARTIN: CLASSIC F1 SPECIAL (C4, 9pm), where the lovable Lincolnshire speed freak (right), an avowed two wheeler, prepares to race Jenson Button around Silverstone in an actual car, is great fun, provided you can get past all the technical talk.
And there’s quite a lot of that. Each guy will drive a classic Williams vehicle from the Eighties, specially restored, so Guy, while preparing, casts his eye over some archive race footage.
“Yeah, obviously, that’s a three-litre naturally aspirated engine,” he observes at one point, “and it’s racing up against a turbo-charged 1.5-litre and it’s just getting smoked everywhere. Smoked, y’know…” You’ll enjoy this show most if you happen to know what the heck the man’s on about.