Editor’s note: The below contains spoilers for Slow Horses Season 4 Episode 5.

Slow Horses’ fourth season is shaping up to be one of its most exciting and revealing yet. It’s an excellent season that centers around the clandestine heritage of Jack Lowden’s River Cartwright. Always the series protagonist, Season 4 reveals that River’s grandfather and MI-5 legend David Cartwright (Jonathan Pryce) has a family secret that both involves River and ties into the deadly bombing that starts the season. While River goes off the grid to seek out the truth, Slough House head Jackson Lamb (Gary Oldman) undergoes his own investigation into River’s whereabouts and the antagonists at the end of the story. His investigation takes him into the heart of David Cartwright’s darkest secrets, building towards a thrilling finale and a top-notch Season 5.

In Season 4, Episode 5, “Grave Danger,” Lamb takes David Cartwright to an unlikely locale in search of the truth: a grave site with particular emotional resonance for Cartwright, in the hope of jogging Cartwright’s increasingly spotty memory. Collider sat down with Oldman about the importance of that torturous choice for Lamb, alongside the unexpected difficulties of filming the pivotal scene. Catch Part 1 of our interview with Oldman here, and stay tuned for the series’ exciting finale as it hits Apple TV+ October 9.

Gary Oldman Reflects on Filming ‘Slow Horses’ Season 4 Episode 4’s Graveyard Scene

COLLIDER: The scene that I keep coming back to is that moment where Jackson brings David Cartwright to a graveyard. It’s such an emotional, intense scene. Tell me about that choice, and about the filming of that scene.

OLDMAN: To film it, it was an absolute pain in the butt. I remember it really well. We had clouds, then no clouds, rain, then no rain. Then, rain, then no rain. In the little church there, off to the side of the graveyard, we spent many an hour just sitting there on these damp pews, waiting for the word. “Oh, yeah, the rain has cleared. The clouds are clearing, and we’re gonna shoot,” and you shoot five minutes. “Oh, the rain. We gotta go back inside…” Now with the magic of cinema, of course, they’ve graded it, and it all looks like it’s a constant thing, but it was really stop, start, stop, start, stop, start. It was an infuriating day for anyone who is remotely creative.

However, the actual scene, it’s the only way to get him to talk. It’s the only way to get him to remember. It’s a roll of the dice. Lamb doesn’t really know for sure, but he thinks that, if he takes him into that graveyard, it would trigger something in the memory that, at least for two minutes, 10 minutes, is gonna be somewhat coherent. And it may be the key that unlocks the puzzle, because he realizes he’s not gonna get anything out of it in Standish’s flat. Does he think he’s faking it? Probably the cynical side of him does, maybe. But if he’s gonna get anywhere with this, with Cartwright, then it’ll be there. It’s a long shot, but it’s just sort of another Mick Herron… it’s so good. It’s a really good bit of character.

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

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