As Slow Horses Season 6 is upon us, fans continue to theorize about the upcoming entry of the British spy thriller. The six-episode thriller will begin streaming on Apple TV from next Wednesday, and it will see the team on the run. Thus, the upcoming season is set to be a challenge for Slough House members as Diana Taverner sets them up for another mission.The trailer, which dropped last month, revealed that one character believed to be dead has returned: Olivia Cooke's Sid Baker is back after being declared dead back in season 1. But many fans believe that this return will have a tragic consequence for Slough House in Slow Horses Season 6, as some believe that a character might exit the series for good.The official logline for the upcoming season teases a challenging time ahead for the Slow Horses:"Season six sees the Slow Horses on the run as Diana Taverner embroils them all in a fatally high-stakes game of retaliation and revenge."Who are the characters who might leave Slough House in Slow Horses Season 6?vas @R1VERCARTWR1GHTLINKI’m sure this is random and doesn’t mean anything serious is going to happen…A fan posted a Slow Horses Season 6 teaser in which we see the faces of three specific characters being marked: Louisa Guy (Rosalind Eleazar), J.K. Coe (Tom Brooke), and most surprisingly, River Cartwright (Jack Lowden). Here is why these three characters might exit the British series for good:LouisaRosalind Eleazar as Louisa Guy | Image Via: Apple TV/www.apple.com/tv-pr/originals/slow-horses/Louisa has been a part of the Slough House ever since the first season, and her most dramatic arc was in season 5, as she was given a six-month mental health break in the very first episode. Rosalind Eleazar returns in Slow Horses Season 6, as we assume that she has dealt with Marcus's death.She also expressed a desire to resign from the spy game altogether in the season 5 premiere. Therefore, this storyline was probably setting up Louisa's exit from the Apple TV series altogether. Or we can see her character meet her end because of the six-month break, as she might have lost her combat experience.J.K. CoeTom Brooke as J.K. Coe in Slow Horses | Image Via: Apple TV/www.apple.com/tv-pr/originals/slow-horsesJ.K. Coe was introduced in season 4 as a former operative who suffers from PTSD. Despite his unassuming demeanor, he can inflict fatal injuries when it is time to step up. He is easily the most dangerous operative in the Slough House, and the only way the team can suffer a blow is if he is taken out as they are on the run.River Cartwright View this post on Instagram Instagram PostRiver Cartwright is one of the key protagonists of Slow Horses, which is why he is also the least likely candidate to exit the spy thriller. But it should be noted that Jack Lowden's name has been doing the rounds as the next James Bond. These rumors gained further steam this week as Gary Oldman claimed that the next James Bond has been cast.The actor even went on to support Lowden if he was cast as 007. If that's indeed the case, it would make sense that the Slow Horses Season 6 team would kill off River so that Lowden could play the new James Bond.Who do you think will die in the upcoming season of Slow Horses?