Since the very first episode of HBO‘s War, Johnny Warren (Archie Renaux) has been living (a highly illegal) double life. While it appears as though he’s just another talented young associate helping his bosses at Taylor & Byrne represent movie star Carla Duval (Sienna Miller) in her messy divorce case, he’s actually a mole for the other side. Since War Episode 1, he’s been feeding secrets to his handler, David Schill (Miles Jupp) at Cathcart & Sons, aka the law firm representing Carla’s ex Morgan Henderson (Dominic West).

Johnny’s carefully constructed spy game comes falling apart in this week’s episode of War — though not in the way you might think.

**Spoilers for War Episode 6 “The Simple Act of Paying Attention,” now streaming on HBO Max**

War Episode 6 “The Simple Act of Paying Attention” opens with the other two associates on the case — Molly Giordano (Emma Laird) and Saeed Masood (Shaheen Jafargholi) — piecing together that there’s a mole in their midst. While Johnny does come under scrutiny, he eventually convinces Serena Byrne (Phoebe Fox) and Nicholas Taylor (James McArdle) that Saeed was the traitor.

However, War Episode 6 ends with Serena figuring out that Johnny is actually the snake in their midst…and it all comes down to one Keanu Reeves “quote” that David Schill loves.

“Well, the simple act of paying attention can take you a long way,” Johnny quotes. “You know who said that?”

Serena pauses and then turns. “Yes. David Schill.” And it’s obvious that Johnny’s been made.

War Episode 6 Ending Explained: Does Serena Know Johnny’s the Mole?

Yes, she definitely does. When DECIDER spoke with the cast of War, Phoebe Fox called the moment “a devastating betrayal” for Serena.

“It was so scary, oh god, it was so scary,” Archie Renaux said.

“I was really looking forward to doing that [scene],” Fox said. “When I read it, I was like, ‘Whoa! Great.’ Then actually to film it was quite complex. The choreography was quite hard, wasn’t it? In the end, I think I got one take on that.” 

“People watching it will be like, ‘What choreography?’” Renaux quipped. “But on the day, there was someone coming out, and just the way that it — for the line to stop you and turn around — “

“You had to be stopped by an SA and the SA had to cross the right. Yes, it was one of those things that — you’re totally right — watching it you’d have no idea, but we spent a lot of time being like, ‘If I take one step and you take two steps.’”

“The SA comes out, on this line, like, no, too early, I’ve got it,” Renaux said.

“But it’s such a good moment and I really didn’t see it coming,” Fox said.

“It’s great because he’s done the hard part, everything else is done.” Renaux said. 

Phoebe Fox also shared that the betrays stings more for Serena because she thought so highly of Johnny; so much so that the actress asked War creator George Kay to add it to the show.

“I think we’ve set up that we have a relationship, that we have a connection actually,” Fox said. “We don’t dwell on it really in the series, but we’ve sort of —”

“Out of the two bosses for Johnny, Serena is definitely the one that looks on him more fondly,” Renaux said.

“I asked George to put a bit more of that in there. I said, ‘I think Serena really should go out to bat for Johnny.’ Because in my mind, a lot of the other characters have had quite privileged upbringings. They’ve come through the public school system and have been funneled into Oxbridge, and I don’t think that is Serena’s background,” Fox explained. “She’s like the girls I went to school with who were just very clever girls in a fairly average state school, who were just clever enough to get into a top university, but had to work quite hard for it.”

“I think that she sees an inkling of a similarity there with Johnny. So, in a way, the betrayal is like…”

“Gut-punching,” Renaux said.

Of course, since this is War, there is an undercurrent of irreverent fun to the twist.

“It’s such a funny line as well,” Renaux said. “It’s so random, because I remember reading the first bit, you’re like, ‘What? That’s interesting. That’s cool, I like it. Did Keanu actually say that?’ And it’s funny that Johnny’s remembered it and gone, ‘That was actually quite a good one –’”

Fox said, “You don’t think the whole series is gonna spin on that Keanu Reeves line. “