The first half of season 10 saw Cole attempting to kill Dean to avenge his father's death. However, when it was revealed that he was a monster who devoured people's livers, Cole abandoned his revenge-driven plan. Viewers haven't seen the last of Cole who will be back in episode 15 named "The Things They Carried".

In the upcoming episode, the Winchester brothers will meet a now amateur hunter Cole who informs the duo that a new supernatural element, called the Khan Worm, is turning human beings into murderers. This supernatural element was created by Eve, Mother of All, and must be eliminated before more innocent lives get killed, according to International Business Times.

Unfortunately, things take a turn for the worse when the worm infects Cole. It is unclear if the brothers kill Cole in order to stop the infection or if they manage to save him. While the brothers tackle the investigation, a sneak peek video by TVLine reveals that Sam will continue to investigate for an antidote for the Mark of Cain. Also, Sam isn't too keen to jump into hunting when Dean shows him a sufficiently weird case to investigate. The exclusive video shows that Sam is reluctant but gives in. Seasoned viewers of the show may recall that Sam's life is in danger even though Dean told him and Castiel that he is fine. Remember, Cain said there is no cure for the curse and he will kill Sam. Can Sam find a cure for the curse before Dean does something drastic?

While Rowena and Crowley aren't mentioned in the episode synopsis, a teaser clip suggests that the mother-son pair will make an appearance in the upcoming episode. Rowena has manipulated Crowley and turned him against the Winchester brothers. Why are the duo back?

Season 10 episode 15 will air on Wednesday, March 18 at 9 p.m. ET on CW.