Hunting witches and the flat expanses of Kansas are both things the Winchester boys are very familiar with.

Oz, however, is way off their radar, even for two hunters who travel as widely as Supernatural brothers.

Nevertheless, it appears Sam (Jared Padalecki) and Dean (Jensen Ackles) will have to tackle the famous lore of The Wizard of Oz while digging into their Men of Letters lineage during the upcoming ninth season.

As revealed in season 8's "As Time Goes By," the sons of John Winchester were meant to be members of the secret Men of Letters organization, a group that worked to catalog and research the paranormal.

Unfortunately, the society fell under attack in 1958, an event that destroyed the organization and propelled the Winchester's grandfather, Henry (Gil McKinney), into the present where he met his untimely death.

Luckily, Henry gave his grandsons the key to the Men of Letters bunker, thus bequeathing the boys with an unprecedented amount of knowledge regarding the supernatural and launching a new story arc.

To fill in a few gaps, the fourth episode of season 9 will take a look back in time at the first men to enter the bunker.

"We very early on have a fun but surprising episode involving the Men of Letters where we'll actually see the first two Men of Letters going to, literally turning the key for the first time in 1935," said executive producer Jeremy Carver, according to the Examiner.

As "Slumber Party" progresses, a hunter by the name of Dorothy will be introduced.

And, yes, it appears she really is from Oz.

"You're going to see that case as something really wonderful to do with The Wizard of Oz. That's as far as I will go," Carver teased to the Examiner. "It's a really fun, relatively elaborate episode that we're all really excited about!"

Supernatural returns to the CW on Oct. 8.

Tags: supernatural