Slow Horses Series Three Review: Gary Oldman Spy Thriller Raises the Stakes – and the Body Count

WARNING: contains spoilers for Slow Horses series one and two.

If Slow Horses aired on BBC One on Sunday nights instead of streaming on Apple TV+, it would be all anybody was talking about. Based on Mick Herron’s series of novels, it stars Oscar winner Gary Oldman (Darkest Hour) as the world-weary and straight-talking Jackson Lamb, a former MI5 agent who is now living out his days at the head of Slough House, the office building to which disgraced spies (known as “slow horses”) are exiled to do menial grunt work after messing up big time in the field.

As we saw in series one and two, Slough House is frequently the playground for MI5’s Second Desk Diana Taverner (Kristin Scott-Thomas, Gosford Park), who likes to get them involved in her dirty off-the-books ops and then blame them when it all inevitably goes wrong. And one of the more recent slow horse arrivals, River Cartwright (Jack Lowden, Dunkirk) seems to find himself constantly at the centre of these dodgy missions, which have so far included foiling a far-right terror plot to behead a hostage and a high-stakes heist by Russian sleeper agents.

This time, the enemy is from within, as power plays and secret conspiracies within MI5 provide series three’s bad guys and peril. It turns out that spies are a ruthless bunch: we see agent Sean Donovan (Sope Dirisu, Gangs of London) conduct a pulse-racing, Bond-worthy boat and car chase through Istanbul only to find a brutal surprise at the finish line that tears his world apart. Believing it to be a MI5 cover-up, Donovan is out for revenge.

Back at Slough House, it’s far more sedate – they’re sorting boxes of old records for a new MI5 archive facility being overseen by Taverner, bored out of their skulls, and almost wishing a disaster upon themselves. But then Lamb realises he’s being followed by a shady character, a kidnap takes place, and the fun really starts.

From then on, Slow Horses packs action into its six episodes: politician Peter Judd (Samuel West, Van Helsing) is back, meddling in MI5’s security protocols with deadly results, a newly power-mad MI5 thug Duffy (Chris Reilly, Wrath of Man) sends a bloodthirsty tactical team on a ruthless “no-survivors” mission, Donovan stops at nothing to get to the truth, and Standish is trapped in the least safe “safe house” of all time – it all passes by in a blur and is over before you want it to be. 

The comedy in Slow Horses is so rich you get lulled into a false sense of security (especially in one memorable scene where a perilous situation almost turns into a Home Alone parody) but the outcomes are rarely lighthearted. This series the stakes are raised high, with much more violence, even greater tension, and a far higher body count as a result, leaving you teetering on the edge of your seat throughout. 

You can’t always forgive the silliness as comedy: there are a few times the plot stretches your patience a little, like Shirley (Amy-Ffion Edwards, Peaky Blinders) somehow remembering all of her colleague’s recent work outfits, Donovan conveniently leaving a Big Wall of Evidence in his flat for the slow horses to find, and the bad guys missing precious opportunities to kill their prey by wasting time trotting out Ooh Aren’t I Awful lines before getting their plans foiled.

But it’s easy to forgive the show these minor weak points because the story itself is still rock solid and as tight as fanciful escapist spy thrillers can be, and Slow Horses clearly isn’t afraid of poking fun at itself.

There’s also character development aplenty among the “horses” themselves – Louisa (Rosalind Eleazar, Harlots) is still grieving Min’s death from series two, Longridge (Kadiff Kirwan, Chewing Gum) and Shirley’s friendship is tested, and River starts to move out of his ex-spy grandfather’s (Jonathan Pryce, The Crown) shadow. Dirisu also makes a big impact in a short time as newcomer Donovan, even if his story isn’t given quite as much depth as he deserves.

By far the most satisfying moment among the existing characters, however, is a powerful, long-overdue stand-off between Taverner and her MI5 superior Ingrid Tierney (Sophie Okonedo, Ratched), which is a deliciously understated portrayal of two brilliant women at war. Standish also gets to shine as a strong female lead, although the series ends with further revelations about her beloved ex-boss Partner, and her rose-tinted view of the Good Old Days of espionage is well and truly wrecked.

All of which lines us up perfectly for series four, which has already been filmed and is expected to arrive in 2024. There are still secrets aplenty to be uncovered, and a sneak peek trailer after the series three credits roll includes some jaw-dropping teases at what’s to come, only reinforcing what an absolutely stellar show this under-appreciated Apple TV+ drama is.

Slow Horses series three is streaming on Apple TV+, with new episodes weekly from November 29th