In 'Back to the Future II', the show will go back to the time before Sam and Dean are conceived, threatening the very existence of the brothers.
Fans of "Supernatural" will get to see Sam and Dean's parents again in the next episode. The angels send Anna back in time to kill John and Mary Winchester before they can conceive Sam knowing that if Sam was never born then Lucifer won't be able to use him as his vessel.
Castiel sends Sam and Dean back to 1978 so they can stop Anna, and the two brothers are reunited with their parents. Mary recognizes Dean as a hunter since he visited her in the past once before but tries to keep the truth from John.
Although the role of John Winchester was portrayed by Jeffrey Dean Morgan in the pilot and few episodes after, he would be filled by Matt Cohen in this one. Meanwhile, the role of Mary is filled by Amy Gumenick who, like Cohen, is back after playing the character in a 2008 episode "In the Beginning".
"Back to the Future II" will air on February 4.