"Supernatural" season 15 is getting closer to its finale. Before that happens, there are a few stories remaining to be told. When the show returns this week, with episode 17, Dean (Jensen Ackles) and Jack (Alexander Calvert) will meet a new ally who is straight out of the bible. Here are a few spoilers for the next chapter of the series. Read on to find out more.

[Spoiler alert! This article contains spoilers for "Supernatural" Season 15 Episode 17.]

After a few demon-hunting adventures, "Supernatural" is expected to return to the core storyline which will involve Winchesters' battle against God (Rob Benedict). The seventeenth episode of the final season is titled "Unity" and it will see Sam (Jared Padalecki) meet the first man of Earth, Adam.

The promo for the upcoming segment teases their first encounter with Adam, as portrayed by Alessandro Juliani. As the teaser opens, Dean looks stunned when Adam appears and introduces himself.

"I'm Adam, first dude off the assembly line," Adam says in the clip. To this, Dean replies, "Garden? Apple? That Adam? Wow."

"The first man, is their last hope," reads the message on the promo.

A voice in the background suggests that all the "events had to happen to get to this moment."

But there is one problem; Dean killed Eve a long time ago. Will this become a concern for their alliance?

Meanwhile, the official synopsis for "Supernatural" season 15 episode 17 suggests that Dean and Jack are about to take an important journey. They hit the road to carry out the final ritual that will take them closer to winning the battle against Chuck. Elsewhere, Sam and Castiel (Misha Collins) will deal with disagreement that forces them to go back in time looking for answers to their questions.

"Dean hits the road with Jack who needs to complete a final ritual in the quest to beat Chuck. A difference of opinion leaves Sam and Castiel behind looking for answers to questions of their own," reads the official description of the "Unity" on CBR.

Supernatural season 11
Supernatural stars Misha Collins, Jensen Ackles and Jared Padalecki The CW

"Supernatural" season 15 episode 17 airs Thursday, Oct. 29 at 8:00 pm ET on The CW.