Episode 5

The British economy is on the brink of collapse. If one more bank goes down, the entire financial system implodes, and Ros Myers goes undercover in the City to flush out the international financier who wants to bankrupt the country. It is her kind of job: sharp suits and lies, with no margin for error. The government is looking for a way to stop it that does not involve admitting how close the edge is.

But the danger escalates quickly beyond money. It becomes clear that Ros's life is on the line as well as the economy, and the episode keeps her out on her own, working a room full of people who would cheerfully destroy her. Every meeting is a trap; the handshakes are negotiations dressed up as politeness. The hour is good at making the glamour feel like pressure. There is no cavalry on a trading floor. She is the operation, and the City is a better prison than most cells.

Christian Spurrier wrote it, Edward Hall directed. Hermione Norris carries the hour as Ros Myers, with Peter Firth's Harry Pearce, Richard Armitage's Lucas North, Alex Lanipekun's Ben Kaplan and Miranda Raison's Jo Portman around her. Gemma Jones's Connie James, Hugh Simon's Malcolm Wynn-Jones, Paloma Baeza's Elizaveta Starkova, Selina Cadell's Gillian Calderwood and Andrew Care's flunky complete the cast.

The episode is a reminder of what Norris does best. Give her a room of predators and a secret, and she will hold the screen without raising her voice. There is a cold pleasure in watching her lie to people who are themselves lying, and the hour trusts the audience to keep up. The financier is a decent villain, all charm and arithmetic, but the episode knows its real asset is the woman walking into his world wearing somebody else's name.

It is a quieter hour than the season has offered so far, and all the better for it. She does not need the Grid to be dangerous, and that is the whole point. The economy can wait. Watching her work is the show.