Supernatural's Book of the Damned will throw the Winchesters into turmoil once more during "Dark Dynasty."

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The flesh-bound tome and its encoded spells could be the closest Sam (Jared Padalecki) and Dean (Jensen Ackles) have come to uncovering a cure for the Mark of Cain. Unfortunately, the powerful and blood-soaked book comes with a laundry list of problems; not least the fact that Dean thinks it was destroyed during "Book of the Damned."

When episode 21 rolls around, Castiel (Misha Collins) will be using his newly replenished grace to keep the peace between Charlie (Felicia Day) and Rowena (Ruth Connell) as the fiery hunter teams up with Crowley's (Mark Sheppard) mother in an effort to decode the cryptic text. Sam and Dean, meanwhile, will have an unexpected - and brutal - run in with the Stynes.

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Although the alliance with Rowena may be ill advised, Charlie's recent experience with her own dark side will give a supercharged caffeine boost to her desire to find a cure for her pseudo older brother.

"That's probably hard but I think that actually gives her more motivation to try to get this Book of the Damned translated because she has seen the darkest part of herself taken over, and she doesn't want any part of that, and she doesn't want Dean to have to go through the same thing with Mark of Cain driving him darker and more evil over the episodes and time," Day informed IGN.

"Dark Dynasty" will air on May 6.

Find out more when Supernatural airs Wednesdays at 9 p.m. ET on The CW. Click the video below to see a preview for the Winchesters' next adventure, "The Werther Project."