The best show on TV is back with an incredibly thrilling new season

Holding a perfect 100% Rotten Tomatoes score, the new season is the thriller's darkest yet.

Based on novels by British writer Mick Herron, the darkly comic spy thriller series revolves around Slough House - an MI5 dumping ground department filled by agents who made career-ending mistakes or made an enemy of management.

Run by the miserable, slovenly but intelligent veteran agent Jackson Lamb (the Oscar-winning Gary Oldman), the department also features River Cartwright (Jack Lowden), a young once up-and-coming agent.

In each season of the show - Cartwright, Lamb and the rest of the reject agents (who are referred to as "Slow Horses") become entangled in a new mystery.

For the new fourth batch of episodes, this mystery involves the shocking bombing of a London shopping centre, as well as River's grandfather David Cartwright (Jonathan Pryce) - a former legend within MI5 now showing signs of dementia.

The first three seasons of the spy series have been hugely acclaimed, a trend that has continued with season four - which currently holds a perfect 100% score on Rotten Tomatoes.

Having watched all six episodes of season four, JOE can confirm that the levels of adoration are warranted.

The new episodes provide more of the spy intrigue, taut action set-pieces and hilarious workplace comedy that Slow Horses has become known for.

This is all the while shedding light on some mysteries that have been percolating since season one of the programme and introducing the series' scariest villain yet, played by Hugo Weaving.

You can read a sample of some of the raves for Slow Horses season four right here:

Empire Magazine: "Darkly funny and tighter than the buttons on Lamb's sauce-stained shirt, this is yet another outstanding season for Apple’s brilliantly unconventional spy series."

FandomWire: "Season 4 of Slow Horses is firmly the best of the show yet, boasting the most exciting and complex story we’ve seen so far"

London Evening Standard: "It’s one of the great shows to come out of Britain full stop. And series four delivers more of the same: a fully realised world, superb script, a stellar cast all at the top of their game and a lot of great action."

Paste Magazine: "One of the joys of Slow Horses is its ability to balance an inherently dramatic narrative with a wry sense of humor. That still exists, but Season 4 is more personal, and, thus, feels more consequential than its predecessors."

Also part of the cast for the fourth season are returning actors Aimee-Ffion Edwards, Christopher Chung, Kadiff Kirwan, Kristin Scott Thomas, Rosalind Eleazar and Saskia Reeves, alongside newcomers Joanna Scanlan, Ruth Bradley and Tom Brooke - all of whom turn in great performances.

The first episode of Slow Horses season four is streaming now, with the other five episodes dropping weekly every Wednesday.

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