Talk about an iconic ending…

Slow Horses Season 6, Episode 2 spoilers ahead.

Slow Horses Season 6, Episode 2, “Daddy Issues,” saw Frank Harkness (Hugo Weaving) taking care of business, Diana Taverner (Kristin Scott Thomas) reluctantly doing an interview for Damien Cantor’s (Harry Lloyd) news station, Moira (Joanna Scanlan) being targeted by assassins, and the return of Sidonie Sid Baker — which was either a surprise or long-awaited, depending on whether or not you’ve read Mick Herron’s Slough House books.

So who is Sid Baker in Slow Horses? What happened to Olivia Cooke’s character in Slow Horses Season 1? What happened to Sid Baker in the books? And how did Sid make her triumphant return in Slow Horses Season 6, Episode 2? We’ve got answers!

Who Is Sid Baker In Slow Horses? What To Remember About Olivia Cooke’s Slow Horses Character:

As noted in our Season 1 recap article, if you feel like you haven’t heard Sid’s name in years, you’re right! The Slow Horses — and viewers — haven’t seen Sid since Season 1, because she was presumed to be dead.

Slow Horses Season 1 finds River, Sid, and the rest of Slough House racing to rescue a kidnapped student. But Episode 1 also saw River and Sid surveilling journalist Robert Hobden (Paul Hilton), which ultimately took a dark turn. As River was staking out Hobden’s house alone in Episode 2, Sid hopped in the passenger seat, and the two shared a heart-to-heart, but when River questioned why Sid was in Slough House, she dodged the question — until someone labeled “Aunt Zadie” in her phone called twice, and she finally picked up.

“I can’t talk at the moment. No. I’m watching him right now… I will, but I have to go,” Sid said to the person on the other end of the line. When she hung up, she revealed it wasn’t her aunt. “There’s a reason why I didn’t tell you why I’m at Slough House… I didn’t just follow you today. That was Taverner, and I wasn’t telling her I was watching Hobden. I was telling her I was watching you… It’s the reason I’ve been sent to Slough House. To keep an eye on you.”

Before we could learn more, someone broke into Hobden’s house, and River and Sid raced to save him. River went inside while Sid covered the front door, and though River rescued the journalist, when the attacker raced outside, a gun was fired, and River found Sid had taken a bullet to the head. As she was bleeding out on Hobden’s stoop, River called an ambulance, and Lamb revealed in Episode 3 that “she might live.” In Episode 4, River snuck into the hospital and found Sid in a coma in her hospital bed. And in Episode 6, Lamb told a devastated River that she’d passed, assuring him, “I won’t forget Sid. Besides, she was the only good one of you.” So what the heck happened?!

Slow Horses Season 6, Episode 2 Ending Explained: Sid Baker Returns!

After realizing Frank Harkness was back and posed a deadly threat to the Slow Horses, River decides to face his “Daddy Issues” head-on, so he gets Roddy (Christopher Chung) to trace what he believes to be a call from Harkness. Towards the end of the episode, Slough House’s current members meet up at Blake’s Grave and plan to go dark to avoid being tracked. But River doesn’t show, and Roddy reveals it’s because he went to his grandfather’s house — where the call was coming from — in hopes of handling their Harkness issue.

The episode’s final minute sees River driving up to his late grandad’s house, grabbing a crowbar, and storming inside shouting for Frank. When he goes to walk up the stairs, however, he’s stopped in his tracks by the sight of Sid standing at the top of the staircase. She flashes a smile, says “Hello, River,” and Slow Horses cuts to black. ICONIC.

Is Sid Alive In Slow Horses? What Happened To Sid Baker In Slow Horses Books?

Yes, your eyes don’t deceive you! Sid Baker is still alive, despite the fact that we were told she died in Season 1. So what happened? We’ll have to wait and see how things unfold on screen, but Sid did return in Book 7, Slough House, and revealed what happened to her after the life-threatening injury she sustained in Book 1.

After River learned of Sid’s death in Season 1, Roddy also gave us a hint that she wasn’t gone for good. “There’s no record of her ever having been at the hospital. And when I pop through my own private backdoor into MI5’s database, there’s no record of her whatsoever,” he told River. “It means, as far as you know, and even as far as Roddy Ho knows — which is a fuck of a lot farther than anyone has ever known — there is gonna be no funeral, or memorial service, or so much as drinks at the pub for Sidonie Baker. Cause no one named Sidonie Baker ever existed… She might still be alive somewhere.”

For those who need a refresher, Season 1’s first two episodes not only established how much trust Lamb (Sir Gary Oldman) had in Sid, but also gave glimpses at Sid and River’s compelling dynamic. The two effortlessly engaged in witty, flirty banter and had an endearing rapport that suggested they could be incredible partners — both on and off the clock. Sid was quick, kept River on his toes, and wasn’t afraid to challenge him. Based on his disappointment in her failing to invite him to after-work drinks one night, he was also clearly crushing. So we can’t wait to see what Season 6 has in store for the two.

When Does The Next Episode Of Slow Horses Come Out? Slow Horses Season 6, Episode 3 Premiere Date:

If you’re counting down the days until the next new episode of Slow Horses premieres, you’re not alone! Mark your calendars, because Slow Horses Season 6, Episode 3 premieres Tuesday, September 29 at 9:00 p.m. ET on Apple TV.

Apple TV comes with a seven-day free trial for new subscribers and has just one ad-free streaming plan available for $14.99/month.

A bundle with Apple TV and Peacock is also available starting at $14.99/month.

Stay tuned for more Slow Horses Season 6 coverage from Decider.