John Byrne's telly week features four new or returning shows: Norwegian drama Occupied, gloomy murder mystery Shetland, music documentary Music Moguls: Masters of Pop, and quirky US procedural iZombie . . .

The great thing about fiction is that it's full of made-up stuff. And just because a plot seems ridiculously unlikely doesn't make it any less believable. After all, most of what happens in real life is often more daft.

If you haven't seen the opening episode of Occupied (Wednesday, Sky Arts), the premise might be off-putting, even though the person behind it is celebrated Norwegian crime writer Jo Nesbø. I guess I'm pleading with you to give it a chance, even though its plot sounds preposterous.

Norway's Prime Minister decides that the best way to combat climate change is to close down the country's gas and oil production. Unfortunately for the Norwegian tree-hugger, the EU doesn't like that idea, so it backs a Russian invasion that aims to keep the energy supply lines open.

In the real world, Russia was understandably miffed by the plot of the series and an official complaint was lodged in the run-up to the show's Norwegian launch last August. They certainly don't come out of the first episode too well, but it was a compelling hour and a very promising opener. Oddly enough, EU big-wigs haven't responded to them being portrayed as anti-environmentalist, undemocratic invasion-backers. Perhaps they were too busy enjoying the show.

After a cracking start, which saw Norwegian PM Berg kidnapped in a helicopter, and pursued by one of the PM's bodyguards, the plot settled. The PM is eventually released, and it emerges that he was informed by video link that the EU-backed Russian invasion was already underway. He's no choice but to accept and sell it to his apoplectic cabinet.

Sounds ridiculous? Certainly. But this is a glossy, well-produced political thriller that will suck you in from the start and should please the Scan-dram fans out there, if not your average Russian expansionist. Great, too, if your favourite fuel is paranoia.

Geographically, Scotland isn't too far away from Norway, so it's been no surprise that Shetland (Friday, BBC One) looks and feels like a Scan-dram. It helps that the lead character, police detective Jimmy Perez, is played by Douglas Henshall. He always looks hungover and morose. And as for Shetland? Well, there's a place that makes the West of Ireland in January resemble the Caribbean.

This third season opens with a mystery around a young man who goes missing on a ferry, and soon develops into a tale of drug-smuggling and other murky business. Perez and his team visit a dead animal artist (don't ask), the gloomy retirement home where the missing man worked, and search the beach where a young boy found some drugs, until the missing person turns up as a dead body at a recycling plant.

It's not exactly a barrel of laughs, and Friday night's hardly an ideal time to watch something so gloomy, but Shetland offers a good yarn that's well-acted. My advice would be to record and watch on a Monday or Tuesday, when the natural mood of the viewer is commensurate with the show.

Much more Friday night fun was to be had with Music Moguls: Masters of Pop (Friday, BBC Four). The first of a three-parter about the people who operate in the shadows of the music industry, this one focused on the pop world's much-maligned managers, a species noted for taking few prisoners and being often as colourful as the acts they handled.

Cleverly, the episode was narrated by Simon Napier-Bell, someone who began managing acts back in the early 1960s, and ultimately achieved the coup of his career when he brought Wham! to China in the mid-1980s, turning them into a global news story. He represented his side with gusto.

Former U2 boss Paul McGuinness, who left quite an impression on the Dublin music scene in the band's early days, was featured, as was 1950s' svengali Larry Parnes. Best of all was Andrew Loog Oldham, who handled the affairs of The Rolling Stones in the 1960s. He provided plenty of colour from his current home, a compound in deepest Colombia, and concluded that it was his destiny to introduce Mick 'n' Keef to the world.

Really, this was a tightly-edited series of yarns from various sides - band members interviewed included Ozzy Osbourne, who married his former boss's daughter - that painted a fascinating picture of a business where there are no rules, change is constant, success is arbitrary and often ephemeral, and no one really knows what they're doing. Programme of the week and no mistake.

I hate ending on a bit of a downer, but I was hugely disappointed with iZombie (Monday, RTÉ2). Coming across in trailers as something of mash-up of Veronica Mars and Pushing Daisies (two of my favourite shows of the last decade), it lacked the smart-ass cynicism of the former and the sharp style of the latter.

The premise was pretty straightforward-weird: Liv Moore (a dreadful pun of a name) is a medical student with a bright future who gets caught up in a zombie attack at a boat party and becomes one of the undead.

Understandably cynical as a result of her condition, she settles into a sullen existence and gets a job working in a morgue, where she can feed on the brains of corpses. That activity provides nourishment, but also provides her with flashbacks and traits from the deceased. In turn, she uses that info to solve murders.

So far, so fun, but the pilot episode lacked any real wit or invention, and iZombie is already in danger of becoming just another quirky procedural, better than Castle and The Mentalist, but only just. Fingers crossed the writers get their act together as the concept is fine, it just needs to be a lot smarter, funnier and inventive in its delivery.

John Byrne