Supernatural season 12 premieres this Thursday (13 October) at 9pm EST on The CW Network. Episode 1 is titled, Keep Calm And Carry On, where Dean Winchester will be overwhelmed to reunite with his newly resurrected mother, Mary.
She will team up with her son Dean, and Castiel to rescue Sam, who was last seen getting shot at by Toni, the Woman of Letters in the season 11 finale.
The official synopsis for the chapter reads as follows:
Dean (Jensen Ackles) is overwhelmed as he comes face to face with his mom, Mary Winchester (guest star Samantha Smith). Meanwhile, Sam (Jared Padalecki) is fighting for his life after Toni, from the Woman of Letters, shot him.
Executive producer Andrew Dabb spoke to TV line about Mary's return and how the Winchester brothers will deal with it. He said, "They're happy and conflicted. It's like a miracle. But the Mary who's coming back is someone who had walked away from hunting but now walks in a world where her sons are hunters. That's the last thing she ever wanted. She's been in Heaven for  years. That's obviously changed her."
Mary will have to adjust to the modern world and technology, teases the producer. "So Sam and Dean are happy to have her back, but they're worried [about] how she'll adjust [to] not only the modern world and technology and that kind of stuff but [also] to them and their lives, and [wondering] if she will be what they have become," Dabb explained.
Confirming that the British Men of Letters will be Dean and Sam's adversary in season 12, Dabb explained, "They're a threat. Lady Toni Bevell has got it in for our boys. But Lucifer is still out there, and whenever Lucifer's on the playing field, it's hard to think anybody is going to top him. Going into this season, it's a dual-pronged approach. [Dean and Sam are] pulled in two different directions."