Slow Horses season four: Taut espionage thriller is one of the great under-appreciated gems

When the first season of Slow Horses premiered in early 2022, it flew under the radar.

Not as many people have Apple TV+ subscriptions and with the glut of new series every day, it’s difficult for anything to break out, even shows with Oscar-winning movie stars such as Gary Oldman.

But over the past two-and-a-half years, Slow Horses has quietly built a dedicated audience who have, in turn, become advocates for its brilliance. Much like its namesake, underestimate it at your peril.

It helps that the series has been prolific in pumping out new seasons instead of demanding its fans wait two years between fresh episodes (and being a British show, it wasn’t impacted by the writers and actors strikes last year).

Based on a book series of the same name, Slow Horses is now up to its fourth season, and across the six episodes, it is a taut spy thriller that keeps you guessing while delivering plenty of draw-your-breath moments.

If you haven’t yet experienced the delights of Slow Horses, the story is centred on the Slough House unit of MI5. This is where they send the agents who have stuffed up on a massive level but not enough to get them sacked. This is where spies get put out to pasture.

The team is run by Jackson Lamb (Oldman), a former field agent from the Cold War era whose disillusionment and lax approach to productivity led to his choosing this run-out-the-time assignment.

The unit also includes River (Jack Lowden), a go-getter agent with family connections to the service who is relegated to Slough House after a monumental mistake involving a training exercise.

Then there is Diana Taverner (forever queen Kristin Scott Thomas), the deputy boss of MI5 who oversees them. Everyone in their orbit has agendas, secrets and sketchy pasts threatening to upend every operation.

For a team that is meant to be doing the thankless grunt work, they often find themselves at the centre of all the action. There have been mysteriously murdered KGB agents, a kidnapped student, far-right terrorists and traitors.

The fourth season has an arc that starts with a personal connection – River’s grandfather David (Jonathan Pryce), a former MI5 legend whose mind is deteriorating due to dementia.

One night, he kills an intruder without fully understanding what’s going on, which sets off a plot involving an MI5-established false identity that has been making unsanctioned trips to France, and a villain played by a menacing Hugo Weaving.

There are also changes afoot at MI5 with a new “first desk”, aka the boss, with in-over-his-head political operator Claude (James Callis, always so good at portraying snaky opportunists) and a fresh head of internal security, Emma (Ruth Bradley).

Before the season is out, there are several gunfights, a bomb, a siege, foot chases and a Terminator-esque killer soldier. Oh, and a charming little French grocery shop, so, you know, there’s a balance.

Slow Horses is exciting and suspenseful TV and one of the great under-appreciated gems of our current streaming era.

Rating: 4/5

Slow Horses S4 premieres on Apple TV+ on Wednesday, September 4