In the opening stretch, a failed MI5 operation lands River Cartwright, played by Jack Lowden, in Slough House, a dumping ground for disgraced agents overseen by the gloriously unpleasant Jackson Lamb. Gary Oldman plays him like a man who’s weaponised bad hygiene. Beneath the insults, the flatulence, and the endless disdain, though, is someone frighteningly sharp. As a kidnapping case starts spiralling into something much larger, this group of cast-offs are forced back into the field whether MI5 likes it or not.
What makes the series work so well is how casually confident it feels. Creator Will Smith and director James Hawes understand the appeal of spy fiction, but they strip away the glamour. London looks cold, cramped, and permanently exhausted. Even the action scenes feel messy in a good way, like nobody here has done cardio in years. You can feel the influence of Tinker Tailor Soldier Spy, but with more sarcasm and far less self-importance.
Oldman is the centre of gravity. He’s hilarious, quietly menacing, and oddly human underneath all the grime. Lowden gives River just enough arrogance to make his failures believable, while Kristin Scott Thomas turns every MI5 briefing into a masterclass in controlled contempt. The ensemble chemistry is excellent because nobody in this world fully trusts anybody else.
The writing is tight, funny, and surprisingly emotional once it settles into the lives of these washed-up operatives. Occasionally the pacing dips between major reveals, but the tension always snaps back quickly. If you’re into espionage dramas that value character over spectacle, this is one of the sharpest on television right now.