Team France make it to London and make an odd discovery. Bill and his new soldier friends realize how little they have in common. Isla is faced with the reality of Bill. Sacha is still evil.

A change in director for the first time this season marks a subtle gear shift for the show. Ben A. Williams loves empty, recently vacated spaces and Howard Overman’s script gives him lots to work with here. The doomed couple who capture a Mechanical and whose story ends as the French team’s begins are especially well directed. Not just the perky, and instantly less perky, cell phone videos but the feeling that people were just here, just alive. That in this profoundly tragic timeline survivors are always just a second too late. Although not for the restrained Mechanical that is far less dead than anyone thinks…

Over in the Bill plot Williams gets a lot to play with too. The double decker bus that a group of characters hide in is a smart piece of physical high ground that’s as fragile as the moral high ground they occupy. Likewise the final rout of the leisure centre is brilliantly handled, a panicked sentry and a spilled drink telling the aliens, and us, just how close they are to wiping everyone out.

But it’s Bill and Isla that haunt you this week. The brutal beating Isla takes at the hands of one of the soldiers is one of those times the show gets perilously close to rolling with bleak joy in its own gore, even though we never see it. That latest in the show’s perennial line-stepping aside, the fact both are dark mirrors for the other is brilliantly and subtly portrayed. Bill looks at the leader of the invading army and sees the first person he can actually materially help. Isla looks at Bill and sees both the monster she hates at a genetic level and the man who saved her life. Gabriel Byrne and Aimee-Ffion Edwards are fantastic here and the final shot could almost be the final shot of the series; an uneasy piece, watchful eyes, violence ever present but not quite manifest. Not yet.

Finally, Sacha’s brilliant plan (holding onto the murder weapon) falls apart as his mother finds it and both she and Emily make some very uncomfortable realizations. The payoff for what Emily and Sacha are to the aliens is barrelling towards us and so far, it looks like the show is going to stick the landing.

Verdict: Terse and grim as ever, but whip smart and shot through with welcome humour (Bill being bad at walkie talkies is excellent fun), this is another good episode of a hard, bleak show. 8/10

Alasdair Stuart