Watch Supernatural season 10 episode 19 online: Sam does a devil's bargain with Rowena and lands Dean in purgatory?

Supernatural season 10 returns with a new episode on 22 April at 9pm on The CW.

Episode 19 is titled The Werther Project, where the Winchester brothers will be seen making another attempt at ridding Dean of the Mark of Cain curse.

Click here to watch the episode online on the official CW website.

The official synopsis reads as follows:

Sam (Jared Padalecki) learns that former Men of Letters, Magnus, once built a magical box and Sam sets out to find it in the hopes it can cure Dean (Jensen Ackles) of the Mark of Cain. However, what he's not prepared for is the deadly alarm system Magnus set up on the box. When Sam opens the box, he puts both his and Dean's life in danger.

In episode 18 the brothers attempt to cure Dean with the Book of the Damned. Unfortunately, it only threatens to make them cross over to the dark side and Dean is still stuck with the wretched curse. By the end of the episode, Sam makes a deal with Rowena, who agrees to help remove the mark, but on her own terms.

In a sneak peek video of the upcoming episode, executive producer Jeremy Carver previews the upcoming episode.

Jeremy Carver says, "At the end of the last episode we saw Sam sitting down with Rowena, and making what looked like a devil's bargain, to find a way to cure Cain."

In the same video, Sam tells Rowena, "I need the mark of Cain off my brother. Something tells me you can crack this book and find the cure."

"Shall we discuss terms" replies Rowena.

Carver also explains that the deceit and secrecy existing between Sam and Dean has started to pervade their relationship.

A new promo also teases that Rowena might double-cross the Winchester brothers, as the synopsis also hints at the danger ahead for the brothers. The video also teases the return of Dean's old friend Benny (Ty Olsson), from his time in purgatory.

He was last seen in the season 8 episode Taxi Driver, wherein he is seen trying to ward off vampires in purgatory, so that Sam can escape.

Will Dean end up in purgatory? Will Rowena double-cross Sam and Dean?

Watch Supernatural season 10 episode 19 for the answers.