Near the outset of Collateral (BBC2), detective Kip Glaspie was patiently explaining a murder scene to her apparently dim colleague.
"Normally you have a body", she told him, "then you work out who they are and who might want to kill them. Only this time - and let me know if I'm going too fast - we don't know who's meant to have been killed, so working out why seems more than normally difficult".
Useful to get that learnt but then this is a crime drama written by David Hare, which means there'll be lots of speechifying and state-of-the-nation ruminations before the murder mystery gets solved (or not) in three weeks' time.
Anyway, the basic plotline is that a young Syrian guy has been shot dead while delivering pizza to Karen, the estranged wife of Labour MP David, who was once the lover of gay vicar Jane, whose current lover (and I hope I'm not going too fast) is a young Asian woman who just happened to have witnessed the shooting but is in London illegally and so can't report what she saw.
Where all this is going is anybody's guess, though already the killer has been revealed as a young military woman, so it's reasonable to expect that dirty doings by MI5 or some other clandestine government outfit is somewhere in the mix. There have also been allusions to the plight of asylum seekers and mentions of grubby politics, and one can only hope that these earnest signifiers of Hare's social and political concerns don't swamp the thriller aspect.
But I'll give it another go on Monday night, if only for the playing by a cast that includes John Simm as the maverick MP, Billie Piper as his alienated wife and, most arrestingly, Carey Mulligan as sarcastic cop Kip.
Still, I got more pleasure from Shetland, which has returned for a fourth season on BBC1, with Douglas Henshall very engaging as doggedly decent cop Jimmy Perez. This time he's probing the case of a local man, recently returned to the island after being exonerated of the murder of a teenage girl for which he'd served more than two decades in prison. Then another teenage girl gets murdered.
As with ITV's Midsomer Murders, we may wonder at the amount of lethal crime in such a tight-knit community, but the landscape is arresting, the characters are intriguing and the unfussy storytelling yields its own pleasures.
Striking Out (RTÉ1) came to its own conclusion with plot twists even dafter than in earlier episodes, culminating in a loony tribunal scene that came to an abrupt end when all the participants just happened to see on their laptops at the exact same instant a damaging tabloid expose of the presiding chairman. Ah, the power of the press. Or, as a viewer remarked in an online post: "WTF is going on?"
Anyway the episode ended with Tara about to confess to cheating ex-boyfriend Eric that she's been having it away with his treacherous brother, which can only mean that another season of this dotty drama is clearly in the works. Oh dear.
At the end of McMafia (BBC1) we were asked to believe that dreary Alex had suddenly turned into Michael Corleone, ruthlessly eliminating his main adversary, seizing control of the global drug trade and coldly shutting his girlfriend out of his life.
Nothing had prepared the viewer for this sudden transformation, and nor could James Norton be mistaken for Al Pacino. And what happened to the David Strathairn character? Did the makers just forget about him?
Will & Grace: 11 Years Later (RTÉ2) saw the return of the NBC sitcom that originally ran from 1998 to 2006 and that, in the opinion of former US vice president Joe Biden, "probably did more to educate the American public" on LGBT issues than any other show.
Over a decade later, Eric McCormack is now 54 and Debra Messing is 49, but they've stepped back into their 30-something feuding flatmates roles as if the intervening years had never happened. And the same can be said for Megan Mullally (now 59) as screechy Karen and Sean Hayes (47) as flamboyantly camp Jack.
My main problem with this reincarnation, as with the original show, is that the zippy one-liners are clever without being really funny, even when in this week's opening episode they were directed at the current incumbent of the White House, whose Oval Office was being redecorated by Grace.
There's more fun to be had in the Cork-based The Young Offenders (RTÉ2), which got off to a raucous start with visual antics and verbal gags that, while very hit-and-miss, were delivered with an exuberance that was frequently disarming.
Alex Murphy and Chris Walley stand out as the show's central messers, but Hilary Rose also registers as sardonic mum Mairead, and creator Peter Foott deserves praise for inventiveness if not consistency.
Also on RTÉ2, Ends Meet is being offered as a homegrown 15-minute cartoon series for adults, or so I would assume from its late-night scheduling. But really there's nothing in this boy, dad and granddad scenario that couldn't be watched by children, though they might well get quite bored by its tame script and somewhat basic animation.
I myself got quite bored with the first instalment of How's Your Driving? (RTÉ1). That may be because I've never driven a car, (I know, I know), but when I watched a young guy trying to negotiate his way around a test track having first consumed a pint of lager, then two pints and then three, I came to feel that there must be more to life.
Some startling facts got stated by presenter Simon Delaney and his team of experts, but this was mostly a road trip to nowhere.