After an action-packed episode and another heartbreaking loss for the Slough House team, Slow Horses Season 6’s finale delivered an unexpectedly agonizing gut-punch in its final minute that will leave viewers asking what the heck just happened and fearing for the fate of a fan-favorite character.

Slow Horses Season 6, Episode 6 spoilers ahead.

Despite losing the heroic Coe (Tom Brooke) and Flyte (Ruth Bradley) in battle, Lamb (Sir Gary Oldman), River (Jack Lowden), Louisa (Rosalind Eleazar), Roddy (Christopher Chung), Standish (Saskia Reeves), Shirley (Aimee-Ffion Edwards), Moira (Joanna Scanlan), and even Reece (Lenny Rush) survive Harkness (Hugo Weaving) and Russian assassins Jim (Kyle Soller) and Jane (MyAnna Buring). After Slough House resumes operations and the Slow Horses meet at their usual spot to honor their fallen joes, viewers wrongfully assume everyone is in the clear. But we almost forgot about someone: Sid (Olivia Cooke).

With minutes left in Season 6’s finale, Standish tells River that his grandad’s neighbor noticed a light on in his house for a few days. Before she finishes explaining, River understands, hops in the car, and drives to David’s house, where a single light is on upstairs, a nod to Sid’s promise that she’d leave the light on for him like his grandad used to. (SOBBING!)

When River enters, he hears the bath running upstairs, so he plans a romantic surprise. As Nick Drake’s “One Of These Things First” plays, he races to make tea, moves the crowbar he left on the counter earlier, and decides to pop open a bottle of wine. As he attempts to perfectly arrange the wine glasses, light a candle, and pop the cork, however, his right hand noticeably bothers him. He starts panting, gasping for air, wheezing. He grabs his phone and tries to call for help, but collapses before he’s able to. The final shot of Season 6 is his still boot on the ground, leaving fans to wonder, “Is River dead?”

So what happened to River in Slow Horses? Need Slow Horses Season 6’s ending explained? Curious if River is dead in the show? Does River die in the Slow Horses books? Will Jack Lowden be in Slow Horses Season 7? Or is Jack Lowden leaving Slow Horses? Here’s everything we know.

What Happened To River In Slow Horses? And What Is Novichok In Slow Horses? Slow Horses Season 6 Ending Explained:

While we’ll have to wait and see which path Slow Horses takes, thanks to the books, we know that a Russian nerve agent, Novichok, poisoned River. As Taverner confirmed earlier in the season, “We responded to nerve attacks on British soil with an action in Russia.” And from the looks of the finale’s final minutes, the nerve agent transferred onto River’s right hand when he grabbed the crowbar, which suggests that Jim or Jane may have planted it earlier in the episode in hopes that someone would grab the makeshift weapon to defend themselves.

How David’s house was hit, and whether the poison was meant for River, Sid, or both, remains unclear. The big question now is: Does River die in the Slow Horses books? So if you don’t want to know, stop reading now.

Does River Die In Slow Horses Books?

Slow Horses has stayed pretty true to the heart of Mick Herron’s source material for major storylines — and even character deaths — thus far, and thankfully in Book 8, Bad Actors, River survives being poisoned! Sid finds him in time, and he spends significant time recovering on medical leave, though he returns in Book 9, Clown Town. So we’re hoping the same happens in the show!

Is River Really Dead In Slow Horses? Slow Horses Season 6 Writer And EP Weighs In

As always, storylines can change in text-to-screen adaptations. So we don’t know if River will die in the show or not. But here’s what Season 6 writer/EP Gaby Chiappe had to say in an interview with TV Insider.

“We don’t know what’s going to happen to him. We know that Novichok has been named, and we know that it has been used within the episode, and we suspect that that’s what it is. And people survive it, but people also die from it. So we don’t know what’s going to happen,” Chiappe said. “You can hear that Sid’s having a bath upstairs. You can hear the water running. So at some point Sid is going to come down. Is she going to come down soon enough to be able to help River? And you have to be really careful touching. It’s a nerve agent that I think permeates your skin. So she’s potentially in danger, but she’s also potentially the reason that — if River does survive, she could be part of the reason that he does survive.”

Hopefully, Slow Horses sticks to the text and is simply trying to build suspense by keeping people guessing, but since Season 7 has a new lead writer in Ben Vanstone, Chiappe hasn’t read the scripts for Season 6, which adds another layer of mystery.

“…I’m not involved, and I am really, really excited about finding out what’s next,” Chiappe said. “So I’m now back with all — I’m on the same status as any other viewer for Season 7, any other viewer who’s read the book.”

Is Jack Lowden James Bond? Will Jack Lowden Be In Slow Horses Season 7? Or Is Jack Lowden Leaving Slow Horses?

In keeping with tradition, after Season 6’s finale wraps, a Season 7 preview airs to give viewers a taste of what Season 7 has in store. If you want a full breakdown of that teaser and everything we know about the Slow Horses season ahead, we’ve got you covered. But related to River and Lowden’s fate, here’s what’s relevant.

The Season 7 teaser kicks off with Standish asking Lamb if he’s heard anything about River, and Lamb quipping, “Yeah, funny enough, I got a postcard. ‘Weather’s lovely in the afterlife. Sunsets to die for. Love and hugs.’” We don’t love the reference to River’s death, nor do we love zero glimpses of Jack Lowden or Olivia Cooke in the teaser, but again, that could all be by design to intentionally build suspense — especially for people who’ve already read the books and assume they know how Season 7 will play out.

While it’s not yet revealed whether Lowden will be in Season 7 or not, we imagine Slow Horses will show the aftermath of Season 6’s final scene, which would presumably feature Lowden in some capacity. And we can’t imagine a season without him! Even if River survives as he does in the books, he could be away recovering for a good chunk of Season 7. But there’s no news that Lowden is leaving Slow Horses.

Though some fans will likely wonder if Lowden’s potential James Bond casting could keep him from Slow Horses Season 7, as the preview confirmed, Season 7 has already completed filming! In fact, the show has already been renewed for Season 8, and production is currently underway. With recent Lowden and Cooke sightings, it seems Slow Horses fans have reason to be optimistic about River and Sid’s post-Season 6 fate.

While an official Slow Horses Season 7 premiere date has yet to be announced, fans can assume the one-season-per-year tradition will continue. Based on recent seasons, it’s also likely that we’ll get new episodes in Fall 2027, as the past four seasons have premiered in November (Season 3) and September (Seasons 4 – 6.)

Which Mick Herron novel will be adapted in Season 7? How many books are in the Slough House series? And what do we know about Slow Horses Season 8? Here’s everything to know about the future of Slow Horses, including Season 7 and Season 8 info, the Bad Actors book summary, what we learned from the teaser at the end of Season 6’s finale, and more.

Stay tuned for more Season 6 finale coverage from Decider and updates on Slow Horses Season 7.

Slow Horses Season 6 is now streaming on Apple TV.