"Supernatural" season 12, episode 4 spoilers reveal that Sam and Dean decided to set out once again on a mission as priests to discover a mysterious couple in the area. Meanwhile, it's a heartbreaking episode for the Winchester brothers as Mary also decides to leave his sons for now.

Sam And Dean On Mission

"Supernatural" season 12, episode 4 titled "American Nightmare" is another shocking chapter in the lives of Men of Letters members. Sam (Jared Padalecki) and Dean (Jensen Ackles) decided to set out on a new mission as priests to solve the mystery surrounding a devout religious couple. As the Winchester brothers go on with their mission, they will discover that the couple has been living an off the beaten track kind of lives. As the official trailer for episode 7 reveals, dead bodies are swarming everywhere. It seems like cadavers are part of the couple's grimy collectibles. Do they just collect these dead bodies or there's something deeper behind this fetish?

Mary Leaves Sam And Dean

Six episodes after Mary (Samantha Smith) was resurrected, the character is now slated to leave again. It should be a heartbreaking moment once more for Sam and Dean to see their momma go. According to spoilers, Mary's decision might have something to do with the brothers' quest to pin down a mysterious family behind those corpses.

"Supernatural" Season 12, Episode 3: The Foundry Recap

In episode 3 titled "The Foundry," the Winchesters decided to set out on a mission to discover the hidden mystery of an abandoned house where a crying baby can be heard from anywhere near. As the hunters have found out, the crying baby led to a shadowy death of a student. On the other hand, Castiel (Misha Collins) was down to his last-ditched option, Crowley (Mark A. Sheppard), in his battle against the fallen angel, Lucifer (Rick Springfield). It can be remembered that the two characters have a lot of differences that separate them widely.

"Supernatural" season 12, episode 4 airs Thursday, Nov. 3 at 10 p.m. on The CW.