Slow Horses, series four: 'swaggering' spy thriller returns

Based on a series of spy thriller novels by Mick Herron, "Slow Horses", which has returned to Apple TV+ for its fourth series, is a "jewel in the streaming service's crown", said Neil Armstrong on BBC Culture . The show about a rag-tag group of MI5 rejects has "lots to say about the UK", with its "London of grotty takeaways, depressing pubs and bin bags full of rubbish all over the streets".

The intelligence agents have each mucked up a mission in their own way or are just deemed no longer suitable to work at the Park, MI5's fictional HQ in London's Regent's Park . It's up to Jackson Lamb (Gary Oldman), who is in charge of misfit-central Slough House, to get the MI5 rejects to quit.

The action is exciting; the opening episode features a terrorist attack, a jaw-dropping killing and some "brilliant Jackson Lamb zingers".

The so-called "slow horses" who have been put out to pasture have hitherto behaved as if they don’t give two hoots about each other, said Fran Hoepfner in Slate . But here, their admiration of each other comes through, though efforts toward developing relationships between some of the more minor characters "ring hollow" and the "pivot to personal" is a bit of a "shaky turn" for a show that excels at both action and comedy.

But Lamb's band of second-rate spies finally show what they are capable of when they "stop bickering for all of five seconds", revealing a group that is "stronger, sharper, and more capable than ever".

Good job then, as the new villain of the piece, Frank Harkness, played by Hugo Weaving gives them a run for their money. Weaving runs a mercenary home for boys, one of whom could be responsible for the bombing that kicks off the series' proceedings.

Alongside this new threat, agent River Cartwright (Jack Lowden) and his grandfather David (Jonathan Pryce), a former MI5 grandee, both find themselves on the run from The Park and the group of mercenaries operating out of France.

Notable new faces this season are the super keen Moira (Joanna Scanlan, known for her roles in Armando Iannucci’s "The Thick of It" and "In the Loop") and the slick Claude Whelan (James Callis), who comes up against the brilliant Diana Taverner ( Kristin Scott Thomas ). Callis's depiction of "slippery, half-confident upper management" is as good an example as you'll see, said Nick Hilton in The Independent .

If the fourth season of the show proves anything, it’s that these two characters – River and Lamb have given "Slow Horses" a "beating heart". Oldman as Lamb, who is "as corpulent and corrupt as ever" is "impeccable".

Despite its sometimes muddled plotlines and "repetitive bickering", "Slow Horses" establishes itself as "innovative time and time again", said Hoepfner in Slate. For all the chances they have to escape Slough House, "there’s a reason why they" – i.e. the slow horses – "(and we) keep coming back".

"Slow Horses" is both "swaggering and well-defined" and has emerged as one of the "most consistent, and consistently enjoyable, shows on TV", said Hilton in The Independent.