Sacha and Bill clash with disastrous consequences. Bill makes a new ‘friend’. The French team make it to the Channel but at a terrible cost.

This is a show that promises nothing. There’s no safety, no convenient plot armour and from the opening (barely) off screen murder of a child survivor to the horrific way Ash is killed, this episode drives that home every chance it gets. This war is driven by the seething, raging hated the invaders feel, and that hatred, and brutality, fully bare their teeth this week. Much like the reveal on what the Mechanicals do to pregnant women last season, this is going to turn some people off. Act accordingly and based on your comfort.

So, the first horrific thing that happens is the French team witness the murder of a child by the Mechanicals. Outnumbered and unable to do anything they observe and, traumatized, press on to the coast. There’s a lovely conversation between Victor and Catherine about the universe and regret that’s both the most Gallic thing the show has done to date and weirdly reminiscent of the ‘It’s the end of the world, Lee’ moment from the Ron D. Moore Battlestar Galactica miniseries. The world is ending, that focuses the mind and shows you what’s important. Which is perhaps one of the reasons why Victor sacrifices himself to save the others in a chilling closing action sequence. Pursued through a forest of freight containers, the French team are hurt and pinned down until Victor makes the ultimate sacrifice. Last week he was ready to die alone, this week that death means others live. It’s a short, brutal arc but it has emotional resonance for days.

Meanwhile in London, Mathie Torloting steps into the light as a major player. Sacha has always fizzed with threat but the slow burn build to him trying to kill Bill is brilliantly handled and Torloting has your eyes the whole time, quite an achievement given his screen partner is Gabriel Byrne. His later scenes in particular are terrifying, dead eyed and calm even as the man he’s killed slowly expires in front of him. His response to ‘it’s not too late’, with ‘Actually I think it is’ is a series highlight so far, delivered with the calm of a cat watching a fish gasp for air. The fact his victim is Ash, poor kind, doomed Ash makes it all the more terrifying. It also throws the series’ choices into stark relief. Aaron Heffernen’s affable medic has been the heart of the show and here he dies, and it takes a long time and is utterly mundane and horrifying. Plus it’s worth noting that Bill makes no effort to raise the alarm or double back and help Ash. No one’s the hero here, or fully the villain, well not anymore.

Verdict: This is a hard watch. Brutal, offhanded and cheerfully willing to down characters that a kinder series would spare, this is a tense, gripping hour of TV. It’s arguably the best episode of the show to date, but it is so very very grim. Brace for that and you’ll be fine. 9/10

Alasdair Stuart