John Byrne's TV week includes the latest le Carré adaptation and the return of Lena Dunham's zeitgeisty Girls.

Reviewed: The Night Manager (Sunday, BBC One); Girls (Monday, Sky Atlantic); Togetherness (Monday, Sky Atlantic)

When it comes to storylines, John le Carré will always be considered a very safe bet. Over the years, many of his books have been adapted for TV or film, and The Night Manager (Sunday, BBC One) is the latest. Originally published in 1993, it's his first post-Cold War novel, detailing an undercover operation to nab an international criminal.

There had been two previous attempts at turning the story in a film, but both failed to be completed. On the evidence of last Sunday's opening episode, it looks likely that this BBC-AMC collaboration will be the proverbial third time lucky. It worked very well on every level.

A stunning cast is led by the permanently impressive Tom Hiddleston as the titular Jonathan Pine, a former British soldier who is recruited by Angela Burr (Olivia Colman, another flawless practician), an intelligence operative, to spy on arms dealer Richard Roper (Hugh Laurie), Roper's girlfriend Jed (Elizabeth Debicki), and associate Corcoran (Tom Hollander).

Viewers first meet Pine as he sashays through a war-torn Cairo, as the battle-hardened vet gets to work as a night manager at a posh hotel in the Egyptian capital, and gets to wear impeccably-knotted ties. After the girlfriend of a local big noise gets him to photocopy sensitive documents linking him to arms dealing with Richard Roper, Pine gets romantically involved with her while notifying British intelligence of the situation. He also tries to provide her with safe passage out of Cairo, but she ends up a corpse and Pine is riddled with anger and guilt.

Fast-forward a few years and Pine's now working at a posh hotel up a snowy mountain in Switzerland, and Roper arrives, Third Man-like and out of the shadows of his philanthropic public image. There's an underlying sociopathic nastiness about this seemingly benign individual, a trait that exploits Laurie's skill-set to great effect. We're going to enjoy hating this guy.

Immediately, it's a crucial moment as Hiddleston's sharp-suited, almost 007-like demeanour brushes up against Laurie's deliciously ambivalent portrayal of Roper, who's clearly a wolf in sheep's clothing. Naturally, the battle commences pretty much immediately as Pine enjoys a fruitful root through Roper's rubbish.

This has all the hallmarks of a classic series, and looks like it was budgeted by an unusually benevolent Russian oligarch. I won't be going anywhere but the sofa over the next five Sundays. The only complaint I'd have is that there wasn't enough Olivia Colman on camera – but there never is.

Moving from one wonder woman to another: Lena Dunham is back with her self-paved path to stardom, Girls (Monday, Sky Atlantic). Last year's fourth season was a bit of a mixed bag, which kind of sums up Dunham's breakthrough show. It's always been a little uneven, though the best bits have been so brilliant I'd forgive any failings.

Certainly, the four main female characters have been great fun, as has been Ray, Shashona's delightfully cantankerous ex. Given that Adam Diver is now the new Evil Personified in Star Wars, I hadn't expected him back as Hannah's former boyfriend Adam. But there he was, looking all dapper.

The season five opener was all about Marnie's wedding, a hugely fraught affair, and the episode was written and directed by Dunham, who could well move into movies once Girls ends with its sixth season.

Dunham's maturing as a writer and a director are obvious, although the same couldn't be said for most of the characters, still prone to bottomless pits of self-pity and narcissism. Determinedly self-absorbed, that makes for a largely engrossing half-hour.

Marnie's fiancé Artie may not be the brightest or the bravest – for example, he dives into a large pond/small lake in dread of his impending nuptials – but Marnie appears oblivious as she obsesses, with an increasingly manic disposition, about make-up, her headdress, hairstyles and the general look of her wedding.

Meanwhile her mother (a superbly deadpan Rita Wilson) ignores all that and rattles on about the biggest regret of her wedding photos. It isn't the fact that she was standing next to a man who turned out to be an unfaithful sex addict, but rather that she used shoulder pads, a sartorial defect that almost defines the 1980s. Like mother, not like daughter. Marnie may be both neurotic and right.

Hannah's relationship with Fran is far from centre stage, but that's okay. Mostly, this episode is about reacquainting viewers with the characters while reaching a defining moment in the story of four twentysomething girl friends growing up in New York. Marnie's wedding, which is about to begin as the season five opener ends, is a sign that profound change has arrived. Or everyone's just getting older.

No one seems to know that yet, so here's to having some fun watching Hannah and co cope with real adulthood. The angst may be coming to an end, with middle-aged disappointment, disillusionment and despair just around the next decade or so.

Whatever the future holds for the characters in Girls, it's probably not going to be far removed from what goes on in Togetherness (Monday, Sky Atlantic), the Duplass brother's comic drama about a group of fortysomethings struggling to prevent their personal dreams and private relationships from falling apart.

It stars Mark Duplass, Melanie Lynskey, Amanda Peet and Steve Zissis as the two central couples and if last Monday's season two opener is any kind of barometer, this show is becoming unmissable. Most of the scenes are of couples, there's a lot less talk than you get in Girls, because these are damaged grown-ups. Experience helps you keep your gob shut now and again.

Togetherness has been labelled a sad-com, and that's pretty close to the kernel. It's not depressing though, and you find yourself rooting for everyone because they're essentially decent people who are prone to screwing-up. Yep. Same as the rest of us.

Compared to shouty US shows such as New Girl or 2 Broke Girls or nearly every sitcom around, Togetherness offers something genuinely empathic and hugely engaging. It has cult status carved all over its clever clogs, but it isn't clever-clever, just smart in how it observes relationships. It's well worth investigating a show that unfortunately just doesn't register on the TV radar.

As the theme to Malcolm in the Middle put it: life is unfair.

John Byrne