By Chancellor Agard
January 26, 2017 at 09:58 AM EST
Dean Buscher/The CW

Over the past 249 episodes, we've seen Sam (Jared Padalecki) and Dean (Jensen Ackles) literally go to hell and back while saving the world from things that go bump in the night (and the occasional apocalyptic event). However, when Supernatural returns Thursday with episode 250, we'll find the boys — who were arrested for the attempted assassination of the president in the midseason finale — in a new kind of hell: a high security government prison.

"They're kind of in a very real version of hell in some ways," showrunner Andrew Dabb tells EW about the Winchester brothers' latest stay in prison, which is more serious than their previous encounters with the law because "they're basically being treated as terrorists. They are in our version of Guantanamo, this kind of black site. There are no visitors. There's no cafeteria. It's all solitary, all the time."

In the winter premiere, we find out that Sam and Dean have been behind bars for six weeks, which is a long time for these brothers to be off the board. "I think one of the big things we're kind of leaning into with this episode is that the Winchesters started off as two guys in a car driving around killing ghosts and vampires, and they've really evolved into the axis upon which the fate of the world turns in a lot of ways," says Dabb. "We'll sort of find that [there are] things Sam and Dean could've prevented and they didn't on the monster side of things."

Thus, Sam and Dean's absence creates a power vacuum, which the British Men of Letters are more than happy to fill. "When Sam and Dean come back after this period of time, they're walking into a world — it hasn't turned a 180, but it's a little different than when they left it," says Dabb.

This will lead to the brothers having more interactions with the British Men of Letters, which will end up complicating what they think about them. Yes, there's a lot of conflict, but the boys also realize that there is some common ground because they all have the same goal, which is to keep people safe. However, they differ when it comes to their methods.

"The question for Sam and Dean this season — and the question that the British Men of Letters really put into sharp focus — is to what extent do the ends justify the means?" says Dabb. "As Sam and Dean get back into it, they're going to certainly see the negative side of the British Men of Letters, which is really all they've seen so far, but they're also going to see that these guys actually know what they're doing and they're actually doing okay things."

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To be fair, Sam and Dean have debated "do the ends justify the means?" questions in earlier seasons, but this time will be different because they're not only on the same page, but because of their experience over the past 11 seasons, we've seen the guys learn that not all monsters are bad. For example, the brothers routinely team up with Crowley (Mark Sheppard), the king of hell; and one of their best friends, Garth (DJ Qualls), is a werewolf. But, as Dabb notes, if the Men of Letters had their way, they'd kill Garth just because he's a werewolf.

"Sam and Dean have inhabited what, for the British of Men Letters, who are a more dogmatic about things, is a the moral grey area," says Dabb, adding that this will definitely become an issue when the guys turn their attention to dealing with the nephilim, i.e. Lucifer's child growing inside of Kelly's (Courtney Ford) womb.

"Yes, this is the child of Lucifer, but does this mean the child is going to be born evil? Does that mean the child could be come a force for good because it is powerful, because at one point Lucifer was good? It's not Rosemary's baby. It's not somebody that's going to give birth to this thing that is evil full stop. I think there is a real question of what do Sam and Dean do if they catch her?" says Dabb. "If you only land in the black and white, this is a bad thing and this could be a bad thing, and you take care of it. If you're a little bit more morally sophisticated as our guys are, I think it raises a lot more questions."

Supernatural airs Thursdays at 8 p.m. on The CW.