Dean and Sam don't know just how long it's been since Charlie was taken - she wasn't really involved in this case, so when she hadn't come by their hotel room to drop off the lunch and reference book she'd said she would, they hadn't thought much of it. Then, Dean had tried to call her about the case she was helping them on, and when she didn't answer... well, then they found her car, abandoned, and they quickly realized what must have happened.
She's been a huge help on their cases, but she's never been what you could call a strong player out in the field, so Dean spends a lot of the time they search for her going out of his head worrying about what's been done to her. He's half convinced they're already too late, that the witches have realized Charlie's no use as a sacrifice so they've offed her and dumped her body somewhere for them to find, and - no. God, no, not Charlie.
But then they get a lead on the coven's headquarters, this old abandoned warehouse, which is just typical. At least there aren't random chains and hooks hanging around, Dean thinks as they sneak in. There's a lot of crates stacked up seven or eight feet high, though, so he and Sam split up to investigate the individual rows. Dean finds a lot of magical paraphernalia, weird ingredients and spellbooks and shit, but no actual witches to speak of.
Then he hears a faint voice - familiar, Charlie's; thank god, she's not dead - and approaches what must have been office space back when this warehouse was actually in use. The door is closed, hence the muffled sound, but when he crouches down to listen he notices it isn't locked. Weird.
Charlie doesn't sound hurt, but he doesn't want to take any chances. "Sam," he barks, quiet as he can manage, and twenty seconds later his giant moose of a little brother is crouching down next to him. Dean turns the handle slowly as Sam silently counts to three. On three, he throws the door open and they burst in guns first.
"And remember, if you bleed, you aren't - oh, hey guys!" Charlie waves from where she's perched on top of what must've been the ritualistic altar. Sitting at her feet are half a dozen teenage girls; two older women are tied up in the corner of the room. One's bleeding sluggishly from a head wound, and they're both unconscious. "These are the guys I was talking about," Charlie tells the girls. "They'll take care of everything."
"...Charlie," Sam manages after a minute. "What's going on?"
"I convinced the witches to let me go!" she explains cheerfully.
Dean blinks. "You what?"
"It is crazy how uninformed these girls are," Charlie says, looking seriously concerned. "It started out with me arguing with them about the whole 'virgin sacrifice' thing. I mean, if there's one thing I'm not, it's a virgin," she says with an eyebrow waggle. "But according to their magic, if there's no penis involved, the sex doesn't count. And that's so messed up! Jenny here," Charlie points to a girl with a braid that loops around the front of her head, who waves sheepishly, "was super worried about this one ritual they're planning on doing for Ostara, because she's pretty sure she doesn't like guys, but if they don't have equal numbers of men and women the ritual isn't going to work."
"Yeah, but we talked about it, and we figure the gender balance will even out if they can find a gay warlock to join in. And after we settled that, we started talking about virginity again - don't even get me started on the stuff they thought was true about hymens!"
For a second it looks like Charlie's going to tell them about it anyway, so Sam, quick thinker that he is, points at the tied up women and says, "Uh, what about them?"
"Oh, them," Charlie waves a hand at them dismissively. "They're the only actual dangerous witches - the blood sacrifices and demonic magic and stuff? All them. The rest of these girls are regular pagans that got pulled into this by accident. I figure you guys can take care of them while I finish up the sex ed talk. Sound good?"
"Uh... sure." Sam, looking like he's been struck over the head with a club, picks up one of the witches and carries her out over his shoulder. Dean, feeling a little dumbfounded himself, grabs the other and follows him.
"Is it just me," Dean hisses, "or is this the easiest witch hunt we've ever had?"
"Not just you," Sam agrees. "Maybe we need to take Charlie into the field more often."