What Does 'Slow Horses' Latest Cliffhanger Mean for Season 4?

Editor's note: The below contains spoilers for Slow Horses Season 4 Episode 2.

Season 4 of the Apple TV+ hit spy thriller Slow Horses is two episodes in, and Jackson Lamb (Gary Oldman) and the agents of Slough House are involved in the latest threat to London. The show is based on Mick Herron's fourth novel of his series, "Spook Street," and follows MI5's reaction to the terrorist bombing of Westacres in downtown London. But a second storyline has emerged in Season 4 involving River Cartwright (Jack Lowden) and his grandfather, David Cartwright (Jonathan Pryce), that has driven the plot so far, and it seems as if they are both in a very bad situation after the revelations from the cliffhanger of Episode 2. We have several questions about what it means for both the Cartwright men and Slow Horses Season 4 as a whole, which has also added a devious Hugo Weaving as the villainous Frank Harkness.

How Did the Cartwrights Get Into This Mess in 'Slow Horses'?

In the first two episodes, David mistakenly shoots an intruder who was thought to be River but is later identified as the mysterious assassin and bomber Robert Winters. David has seemingly been suffering from spells of dementia and is unable to give an accurate account of what he was thinking when he shot the man. River arrives at his house and helps him cover up the murder before heading to France to retrace the steps of the man who was sent to kill David. Catherine Standish (Saskia Reeves) has provided a safe house for David, but he keeps babbling incoherently when Jackson tries to get information regarding River's whereabouts. Jackson believes David is playing games and knows exactly what's happening.

Nevertheless, River arrives in Lavande, a small and eerily quiet town in the French countryside. He is able to locate Winters' residence and go through his things but is ambushed by Harkness. Harkness is somehow involved in the Westacres bombing and now wants to prevent River from establishing Winters' association with him. If it wasn't for the help of a mysterious Frenchman with a shotgun, Harkness might have killed River. It looks as if Frank Harkness has River dead to rights when suddenly, an older French man who was seen earlier in the episode tracking River arrives on the scene with a shotgun, forcing Harkness to scurry away from the scene. As River and the man flee from the now burning house, he tries to thank the stranger but is met with the butt of the man's shotgun to his face, knocking him out cold. The two drive away from the flaming house, and the end credits roll, leaving the audience wondering what has just transpired.

The cliffhanger left several questions that will certainly be addressed in Episode 3 and throughout the fourth season. The most pressing question is who is helping River and David Cartwright, if it isn't Jackson Lamb, Slough House, or MI5. The mystery man with the shotgun was seen communicating River's location once he arrived in Lavande, but who is he talking to?

How Is Frank Harkness Involved in 'Slow Horses' Season 4?

Image via AppleTV+

It's great to see Weaving brought into the show in Episode 2 as Frank Harkness, but his presence and purpose are being withheld for dramatic purposes so far. From his accent, he appears to be an American, and up to this point, he has been the man calling the shots behind the terrorist bombing of Westacres to begin the show. Now, he has inserted himself into the Cartwright storyline by showing up in Lavande to attack River, who is searching for answers about Winters. Episode 3 will likely reveal more about what Harkness is trying to hide and what his reason for bombing Westacre could be.

While Diana Taverner (Kristin Scott Thomas) isn't directly involved yet with what is happening to River and David, they are aware of Robert Winters's fake identity that was issued by MI5 some 28 years ago. The Machiavellian and smooth deputy head of MI5 will see her story arc dovetail into the Cartwrights, Lamb, and Slough House as the season progresses, as Harkness and the bombing link the fates of the Cartwrights and MI5.

Is David Cartwright Really Faking His Dementia on 'Slow Horses' Season 4?

Because of her kindhearted nature, Standish has given David Cartwright a safe place to stay, since he shot the intruder and appears to be in a state of shock. He is rambling and saying nonsense, but also has moments of clarity where he is able to identify things. If we have learned anything from the first three seasons of Slow Horses, it's that Jackson Lamb's intuition is never wrong. So, it is likely true when he tells Standish that he believes David is faking his traumatized babbling state.

The question then becomes why David would fake his condition and try to deceive Lamb and everyone else. Pryce is a dynamic actor and is convincing as a frightened and incoherent old man, but David is also a former MI5 agent himself; he could be malingering for a specific reason that will be addressed moving forward.

Slow Horses Season 4 is available to stream on Apple TV+ in the U.S., with new episodes premiering Wednesdays.

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