Last Night's TV - The Reckoning, ITV1; Twenty Twelve, BBC4

Dial mum for murder

Goodness knows what Fyodor Dostoevsky would have made of it had he been watching ITV1 last night, but there were clear echoes of his epic novel Crime and Punishment in The Reckoning, with nice Scottish ex-nurse Sally Wilson (Ashley Jensen) weighing up the moral implications of committing murder, given that her intended victim was himself a killer who had mutilated a young prostitute and incidentally lived in Gerrards Cross. What Gerrards Cross had done to deserve him, I don't know. Maybe the writer, Chris Lang, once got a parking ticket there.

Lang's script imbued his own decidedly improbable plot with about as much plausibility as it could reasonably carry, and some decent performances, in particular by Jensen, better known to most of us for playing comedy, did the rest, turning what could have been an exercise in unadulterated daftness into a pretty gripping thriller. It concludes this evening, and happily the obligatory "Next Time" trailer before the closing credits didn't undermine the suspense, as, maddeningly, it so often does.

The story began with a fatal stabbing, carried out by a troubled young woman who was later killed in a hit-and-run. You can generally rely on the corpses piling up in ITV two-parters and so it was here, with another character strangled by the fiendish fellow from Gerrards Cross. What links these deaths appears to be a stranger's will in which bequests of £5m are offered on condition that a particular murder is committed. That's what happened to Sally, who almost did what the rest of us would do on being asked to bump off a chap from Gerrards Cross for five million quid – namely walk very quickly in the opposite direction, ideally towards a police station.

But she didn't. Conveniently for the plot, Sally has a cancer-stricken teenage daughter, whose survival depends on expensive treatment in America. She also has a partner, Mark (Max Beesley), an ex-policeman who nudged her towards accepting the contract, at least if they could show that the intended victim, Richard Bury, was dastardly enough to deserve a bullet in the chops. Even more conveniently, Sally now works in the credit-checking department of a bank, and so was able to see from Bury's incomings and outgoings that he was a regular user of prostitutes. Then she took her life in her hands and went to Gerrards Cross after dark, where she loitered outside Bury's handsome house, and watched a happy family scene that was nicely illuminated both for Sally's benefit and ours, Bury having obligingly followed the first rule of television drama and neglected to draw the curtains.

That's more or less it so far, but for another few fishy details that may or may not be red herrings. It could be that the dead man with the strange will has a grudge against her, since we learnt that Sally had been cleared of negligence charges at the hospital where she once worked. This useful titbit of information came when her partner, Mark, looked up her story on the internet, which showed either that he doesn't know her very well, or that there's more to him than meets the eye, or that Lang couldn't think of any better way to give us Sally's backstory, internet search engines being almost as dramatically useful as open curtains. Most likely, it's a combination of all three. Whatever, I hope the story ends more happily for Sally than it did for Raskolnikov in Crime and Punishment.

As for last night's other Sally (Olivia Colman), personal assistant to Ian Fletcher (Hugh Bonneville), head of deliverance at the Olympic Deliverance Commission in the always amusing and sporadically very funny Twenty Twelve, I yearned for the happy ending that she herself seemed to yearn for, a meaningful clinch with her boss. Alas, the final episode didn't yield the romantic encounter it had promised, despite Sally continuing to show much more devotion to Ian than he got at home from his needy, nagging, pixellated wife.

It's hard to think of a spoof documentary that has been more fortuitously timed than Twenty Twelve. The first episode poked fun at the Olympic countdown clock, and within less than a day the real clock had malfunctioned. Since then, there's been no end of argy-bargy concerning the future use of the Olympic stadium, with the decision to hand it to West Ham United robustly challenged by Tottenham Hotspur and Leyton Orient. Oh, and marathon man David Bedford has resigned, citing general ineptitude. So it has taken only a very small leap of the imagination into the fictional world of the ODC, whose head of sustainability (Amelia Bullmore) was last night confronted by a man from the London Wildlife Stag Beetle Outreach Project, worried that clearing an area of tree stumps would wreak devastation among his beloved beetles.

Similarly outraged was Tony Ward (Tim McInnerny), a volatile film-maker aghast at the deployment of Greenwich Park for the equestrian events, and the probable daily invasion of "20,000 pubescent girls from second-rate public schools in Surrey with dreadful aspirational mothers". To demonstrate his opposition, Ward had a large pile of horse manure dumped outside the ODC offices, which Fletcher agreed to deal with to "keep it from Seb".

I don't think that's another example of art and life colliding, but it easily could be. Indeed, Ward and Roberts finally came face to face in the Today programme studio, where they were asked a succinct question by James Naughtie, just about the only truly unlikely turn of events in the entire half-hour.