Drone Logic:Vigil S2.

Lots of guns, lots of knives, lots of drones, lots of camouflage, lots of computer screens, lots of passwords, and lots of people arresting each other. More than anything - lots of suspicion. Vigil (BBC1/iPlayer, created by Tom Edge and directed by Andy De Emmony and Joss Agnew) is back after more than two years and this time they've ditched the submarine and found themselves on dry land.

Not that there's many characters left from the first outing. Just DCI Amy Silva (Suranne Jones) and her partner, both in life and in police work, DS Kirsten Lovegrove (Rose Leslie) - and their boss DS Colin Robertson (Gary Lewis). Everyone else is new which is both good and bad. It's good because there were a LOT of people in the first series of Vigil and it'd be bloody hard work trying to remember who they all were. Bad because there a LOT of people in the second series of Vigil and it's bloody hard work trying to remember who they all are.

Make notes. I do. We begin in the fictional middle Eastern dictatorship of Wudyan (a quick Google reveals to me that Casablanca and Rabat in Morocco were used for the filming). Squadron Leader Anthony Chapman (Alastair Mackenzie) is returning to Scotland with suspected liver cancer and Acting Squadron Leader Eliza Russell (Romola Garai) has been installed as his replacement.

On a military base in Scotland, Air Vice Marshall Marcus Grainger (a fairly hammy Dougray Scott) is demonstrating the power and efficiency of some newly developed combat drones to a Wudyani military delegation when it all, very quickly, goes horribly wrong. One drone turns on the soldiers supervising the demonstration and starts shooting, and killing, them.

It's the first chilling twist, but not the last, of Vigil S2 and it's the one that sets the premise for the entire series. Soon enough, Silva and Longacre, now pregnant - giving Silva ample chance to beat herself up for putting her partner (and future child) in danger - are called in to investigate. When soldier Colin Dixon (Anders Hayward) is arrested it's obvious that, even though he was operating - or supposed to be operating - the 'errant' drone, he's not guilty.

The world of Vigil is a world where, quite simply, you can't trust anyone so - soon enough - many others - almost everyone involved - arouse suspicion. There's Nicole Lawson (Shannon Hayes), Callum Barker (Chris Jenks), and Sam Kader (Oscar Salem) - all of whom had worked with Dixon in Russell's team. Each of these people have their own reasons for acting the way they do and they will be investigated in what proves to feel quite a lengthy series.

Colonel Ali Bilali (Nebras Jamali) is a representative of the Wudyani government and, after the drone attack nearly results in the loss of his life, he informs the British military that the Wudyanis are minded to abandon the partnership and cut all funding to Britain. This is a big clue to the direction of travel that Vigil S2 will take us on and it's not long, predictably enough, before things to start to get far more dangerous - and far more convoluted.

Snipers, dead bodies (and lots of 'em), terrorist organisations, a homosexual relationship kept secret for obvious reasons, traitors, torture, kidnapping, an attempt at suicide by cop, a very serious "error of intelligence", and seemingly endless levels of double crossing, Silva and, to a lesser extent, Longacre are thrown into a world which can be thrilling in places and, sadly, a little tiring at other times.

The general feel is, despite the lack of claustrophobia engendered by the submarine setting, tenser than the first series. There are tense chases and moments of extreme jeopardy but there are also moments where you might find your attention drifting off and looking up the football scores or thinking about what you might have for dinner later.

It's a shame. A bit of judicious editing and, perhaps, a cull of some of the more peripheral characters may have done Vigil wonders but that's not what happened. That's not to take away from some of the performances. Jonathan Ajayi plays the head of the drone manufacturer's tech team Wes Harper, Steven Elder plays his boss Derek McCabe, Amir El-Masry plays cocky MI5 officer Daniel Ramsey - who partners (not always easily) with Longacre on the case when Silva jets off to Wudyan, and David Elliot plays tragically crossed former soldier Ross Sutherland.

Credit too should go to Hiba Medina as Anthony Chapman's daughter, Sabiha, underused Orla Russell as Silva's daughter Poppy, and Tommy Sim'aan as Pep Guardiola lookalike Firas Zaman, a Wudyani expat who we first meet hiding in a tree but who ends up being crucial to both the development of the story and to justice, hopefully, being served in the end.

The second series of Vigil touches on many subjects that I find very interesting. Geopolitics, corruption in the highest offices, the evil of arms trading, and the lethal hypocrisy of British foreign policy. It tackles these subjects very well but the occasional longueurs and the confusion caused by such a large cast meant that it could, and should, have been so much better.

My dad was telling me he gave up on it pretty quickly (he's not known for his patience) but I think it's worth sticking with. The last episode ties all the disparate strands together surprisingly neatly and ends on a genuinely powerful, and excoriating, speech. I won't tell you who makes that speech though and, to be honest, I'd be very surprised if you'd be able to guess correctly. Vigil S2 was a journey. Some of it was enjoyable. Some of it was not. The end point made it worthwhile.