Mary (Samantha Smith) has made the decision to quit the hunter's life, which leaves brothers Sam (Jared Padalecki) and Dean (Jensen Ackles) focused on catching Lucifer. Meanwhile, the Winchester brothers work on a case involving a religious family living off the grid.

Previously on "Supernatural" season 12, Mary has decided to break away from the demon-hunting life that Sam and Dean are currently living to take some time for herself and process the new world that she was been resurrected in. Mary woke up to a world without her husband John (Jeffrey Dean Morgan), and it is also one where her two boys are now hunters. She bravely faced this world at first, but she soon felt that taking everything in at once was too much to handle.

With little attachment to his mother, Sam was able to accept Mary's decision without hard feelings. Dean, on the other hand, struggles with the fact that their mother once again departs, this time on her own decision. As much as Dean wants Mary to be safe, he also wants them to be a family, which made it difficult for him to say goodbye to their mother.

But now that Mary has left, there is no other top priority for the Winchesters but to bring Lucifer back to his cage.

In the meantime, Sam and Dean will be working on a case about a religious and odd family in the upcoming fourth episode, titled "American Nightmare."

According to the synopsis released by The Futon Critic, "Sam and Dean investigate a case that leads them to a devout religious family that lives off the grid. The brothers realize that the parents are hiding a huge secret that could destroy them all."

In the episode 4 trailer, the odd family asks the Winchesters if they know God. The brothers will soon find out their big secret and they will do everything to stop them from creating chaos.

"Supernatural" season 12 airs every Thursday at 9 p.m. EDT on The CW.