Slow Horses Season 2 Review: The Cold War Refuses to Stay Buried

Official promotional image for Slow Horses Season 2. Apple TV+ promotional material, used for review and commentary.

Season one of Slow Horses asked what happens to intelligence officers MI5 has written off. Season two asks what happens when MI5 has written off the past.

Adapted from Dead Lions, the second of Mick Herron’s Slough House novels, Apple TV+’s six-episode second season begins with the death of a former agent and a warning about Russian “cicadas”: sleeper agents planted in Britain during the Cold War and left dormant until they are needed. What looks at first like an old spy following an old suspicion expands into several connected investigations, concealed identities and political schemes.

The sleeper-agent plot brings the series’ Cold War inheritance closer to the surface, but its real advance lies elsewhere. The slow horses are no longer merely proving that they retain useful skills. They are discovering that a correct conclusion does not compensate for impulsiveness, poor coordination or damage accumulated over years.

Season two is stronger because it separates competence from control. The slow horses can understand what is happening before anyone else and still approach it badly. This time, the difference costs more than careers.

Cold War Secrets as Operational Debris

Sleeper agents are one of the most familiar devices in Cold War fiction. Their appeal lies in the tension between ordinary appearance and concealed purpose: the neighbour, civil servant or local businessman whose real allegiance belongs to a country and conflict that seem to have disappeared.

Slow Horses uses the idea effectively because the cicadas are more than a puzzle about hidden identities. They expose intelligence work’s inability to draw a clean boundary between past and present. Governments change, alliances shift and agencies reorganise, but people recruited decades earlier do not vanish because the political world around them has adopted a different vocabulary.

The Cold War here feels less like a historical period than unfinished administrative business. Old operations remain unresolved. Retired agents carry information that never entered the official record. Decisions made under one political order continue to shape lives long after that order has supposedly disappeared.

This gives the season an even stronger John le Carré atmosphere than its predecessor. The past is not romanticised as an age of elegant espionage. It survives as operational debris: compromised agents, private grudges and decisions whose consequences were never properly closed.

Old intelligence also creates its own interpretive danger. It may be urgently relevant, or it may be the residue of paranoia. Memories decay and loyalties become harder to read. Once the slow horses accept that sleepers may be active, coincidence begins to resemble evidence and ordinary behaviour acquires a possible second meaning.

The twists exploit both possibilities. The team may be overlooking a carefully concealed threat, but it may also be allowing an old story to dictate what it expects to find. The season repeatedly shifts the boundary between justified suspicion and manipulation without requiring its characters to become foolish simply so that the plot can surprise them.

The machinery is occasionally visible. Several strands converge through coincidence, delayed disclosure and characters entering traps whose architecture becomes clear only afterwards. The momentum carries the story, but the plotting feels slightly more engineered than it did in the first season. What keeps it convincing is the connection between the conspiracy and the history of the Service itself. The danger has grown out of matters MI5 believed it had already contained.

Good at the Work, Bad at Themselves

The slow horses are neither secretly brilliant nor simply incompetent. They notice details others miss, follow leads more respectable officers dismiss and draw accurate conclusions from incomplete evidence. They also act too quickly, withhold information, underestimate people and allow private needs to distort professional judgement.

They are often good at the work and bad at themselves.

Most spy fiction treats competence as a complete personality. The capable agent observes accurately, plans carefully, fights effectively and remains emotionally controlled. Slow Horses breaks competence into incompatible parts. Someone can be an excellent observer and a reckless operative. Another person may understand institutional incentives while misreading emotional loyalty. A correct conclusion can still be acted upon in exactly the wrong way.

Competence in this world is local. It applies to a task, a situation or a particular kind of knowledge. It does not transform a damaged person into a reliable instrument.

River Cartwright remains the clearest example. He has genuine investigative instincts and repeatedly sees connections that deserve attention. His problem is not an absence of ability but his difficulty separating insight from urgency. River wants to act while everyone else is still deciding whether he is right.

That impatience is understandable after his treatment by MI5, but it reduces the value of his conclusions. He does not merely want the problem solved; he wants to be the person who solves it. The desire to restore his professional status continues to interfere with the discipline required to earn it.

The first season revealed that River had not been sent to Slough House simply because he was incompetent. The second makes the more uncomfortable point that the injustice of his exile does not mean he was ready for greater responsibility.

The pattern extends across the team. Courage, persistence and sharp judgement do not exist separately from grief, vanity, loneliness or resentment. Loyalty encourages risk. The need to prove oneself shortens deliberation. Suspicion helps expose deception but can make coordination almost impossible.

The season becomes more brutal because it stops allowing these weaknesses to remain merely comic or professional. Previously, a bad decision might lead to humiliation, another argument with Lamb or further evidence that someone belonged at Slough House. Here, mistakes produce consequences that cannot be administratively reversed.

A rising body count is not automatically proof of realism. Television can kill characters arbitrarily and call the result seriousness. The violence works here because it grows from weaknesses the series has already established. People are endangered not because the story suddenly decides to become dark, but because the qualities that make them useful also shape the mistakes they make.

When an operation deteriorates, the slow horses do not become more professional because the stakes have increased. They remain themselves, which is often the problem.

Jackson Lamb and the Second Problem

Gary Oldman remains the gravitational centre of the series, but Season 2 sharpens our understanding of Jackson Lamb’s competence. The first season established that his neglected appearance and crude behaviour conceal formidable intelligence. The second shows more clearly what kind of intelligence he possesses.

Lamb does not merely understand what each member of his team can do. He understands what each is likely to do after reaching the correct conclusion. His management style consists largely of anticipating the second problem.

River may identify the right suspect, but Lamb knows he will be tempted to act before securing support. Another slow horse may follow a valuable lead while concealing a vulnerability. A technically capable officer may still make a decision based on pride, fear or the need to feel relevant. Lamb plans around these failures because he does not expect insight to repair character.

His cruelty remains difficult to excuse, but it rarely rests on the assumption that his staff are useless. He often knows their abilities better than they do. What he distrusts is their capacity to use those abilities without introducing another source of danger.

The cicada investigation also places Lamb more firmly inside the Cold War world that produced him. David Cartwright, River’s grandfather and a former senior MI5 figure, emerged from the same institution, though from a very different position within it. Cartwright preserved the authority, habits and outward dignity of the old Service. Lamb preserved its suspicion.

Their history adds depth without providing a complete diagnosis of how Lamb became the man we see. The series resists reducing his drinking, hostility and physical neglect to one decisive trauma. His behaviour may be a defence, a performance, an accumulation of damage or some combination of all three.

Season two allows old betrayals and reprisals to surface without turning Lamb’s past into an explanatory checklist. He has spent a career watching institutional necessity used to justify acts that cannot later be acknowledged. He knows how quickly respectable language can be placed around compromised decisions.

His degradation is partly camouflage, but there is no guarantee that the camouflage has not become permanent. The man who encourages everyone to underestimate him may no longer know where the performance ends.

Diana Taverner and Political Control

The political manoeuvring that strengthened the first season becomes more elaborate in the second. Diana Taverner is not yet conducting an explicit campaign for First Desk, but she increasingly behaves as though every crisis is also an opportunity to improve her eventual claim to greater authority.

Her dealings with Peter Judd make that ambition more visible. Taverner understands that operational success is only one currency inside the Service. Access, political protection and control over the official account may prove equally valuable.

She does not need every operation to succeed in a simple sense. She needs events to leave her better positioned than the people competing with her. A failure may remain useful if responsibility can be redirected, embarrassment contained or leverage acquired over someone whose support may matter later.

Kristin Scott Thomas continues to make this calculation a pleasure to watch. Taverner rarely appears hurried, even when events are moving beyond her control. Her composure suggests that she is considering not only what must happen next, but how the outcome will be described afterwards.

The slow horses pursue the immediate truth: who is involved, what are they planning and how can they be stopped? Taverner must also decide who will receive credit, which mistakes can be buried and how the crisis alters the balance of power inside MI5.

This recalls House of Cards at its best, where a conversation can carry as much force as a threat or weapon. Slow Horses, however, is less convinced that intelligent people can control the structures they manipulate. Taverner is formidable, but every political solution creates another dependency. An ally acquired through leverage remains an ally who understands the bargain.

Her manoeuvring is not separate from the espionage plot. It shapes the plot. Intelligence agencies do not suspend career politics during emergencies; emergencies may be when career politics becomes most useful.

Lamb and Taverner remain compelling because each recognises what the other is doing. She cannot persuade him that institutional interest and national interest are naturally identical. He cannot dismiss her because she possesses authority, access and information Slough House lacks.

The slow horses are unreliable in the field. Taverner’s unreliability operates at another level: she can contain embarrassment and redistribute blame, but her solutions are designed to preserve power as well as protect the Service.

Stronger—and Less Charming

Season two gains severity at the expense of some of the first season’s workplace charm. The earlier season benefited from the novelty of Slough House. Meeting the team, learning its hierarchy and watching Lamb collide with Taverner were substantial pleasures in themselves. The central operation gave those relationships direction, but the workplace remained the main discovery.

The second season already has that foundation. It can move more quickly, divide the team across several lines of inquiry and place greater weight on the history connecting Lamb, David Cartwright and the Russian threat. Slough House no longer needs to be introduced; it needs to be tested.

The increased danger weakens the assumption that recurring characters are protected by the structure of the story. Once that confidence disappears, relatively ordinary decisions become more tense. Following a lead alone, delaying a call or trusting the wrong person no longer feels like temporary jeopardy imposed on a secure ensemble.

The action also works because it emerges from investigation and political manoeuvring rather than replacing them. Clues create political problems. Political decisions distort operations. By the time someone starts running, the reasons for the chase have already been established in offices, archives and private conversations.

Physical danger is the point at which institutional choices can no longer remain abstract. The characters do not become more capable when weapons appear. River remains impulsive. The slow horses remain poorly coordinated. Headquarters remains preoccupied with how events will be interpreted.

The six-episode structure leaves limited room for emotional aftermath. The season is willing to impose consequences, but the plot often begins pulling the remaining characters towards the next crisis before those consequences have been fully absorbed. Death changes the atmosphere more decisively than it changes the rhythm.

That compression may partly reflect the institution itself. MI5 continues operating regardless of whether the people inside it have processed their losses. Slough House offers little privacy and even less institutional care. Grief becomes another condition under which the work must continue.

Even so, several moments deserve more space than the season gives them. The brutality is effective because it feels consequential, but those consequences occasionally pass too quickly into the machinery of the next operation.

The first season presented Slough House as the place where MI5 stores the failures it can name. The second shows what happens when that containment breaks down. Agents can be exiled, operations classified and old networks declared obsolete, but none of those administrative acts removes the people, loyalties or consequences involved.

The Cold War does not simply return from the dead. It was never as dead as the institution preferred to believe. The cicadas carry an old operation beyond the political world that created it. Lamb and David Cartwright bring different parts of that world into the present, while Taverner is already turning the latest crisis towards future advantage.

The slow horses stand between them: perceptive enough to recognise the danger, damaged enough to make it worse and human enough to pay for the difference.

Season one showed that Slough House could still be useful. Season two shows the harsher limit of usefulness: being right does not mean arriving in time.