Sam and Dean run into a young version of their grandfather in the latest episode of Supernatural Season 8. We have a photo gallery and videos for those who are looking for a little preview before the episode airs tonight.

Supernatural Episode 8.12: As Time Goes By – "SAM AND DEAN MEET THEIR GRANDFATHER — Sam and Dean are stunned when a man who claims to be Henry Winchester (guest star Gil McKinney), their grandfather, suddenly appears in their hotel room demanding to know where he can find John Winchester. Henry has time-traveled to stop a demon named Abbadon (guest star Alaina Huffman) and was looking for John’s help. Through Henry, Sam and Dean learn more about their father and the Winchester blood line. Serge Ladouceur directed the episode written by Adam Glass."

For those that haven’t caught up on the new season, here’s the original Season 8 synopsis: “Season Eight begins with Dean’s seemingly impossible escape from Purgatory, though Castiel is nowhere to be found. However, Dean isn’t alone. He’s returned with a mysterious comrade-in-arms whose reason for escape is perhaps more than Dean bargained for. Meanwhile, Sam finds himself reconciling the life he discovered while Dean was gone with Dean’s sudden reappearance. As the boys struggle with their unexpected reunion, they make a shocking discovery that could lead them on a deeply personal mission to settle old scores. If only they could agree – is this a “family business” or isn’t it?”

If you haven't watched any of Supernatural and would like to get started, the first seven seasons are now on Netflix. If you’re a bit behind on this season, the last few episodes are on Hulu.