Although Sam wants to focus on finding Kevin and the demon tablet, Dean suggests that they take on a case involving a murderer taking a human heart every six months. Tracking down the crimes from Minneapolis, Minnesota to Boulder, Colorado, the Winchesters discover that all the murders were committed by different people, all with no prior history of violence, and that each likely suspect had an alibi for the other murders. After one of their suspects (Paul Boyle) stabs himself in the eye, Dean learns that each killer had received an organ transplant from the recently deceased athlete Brick Holmes. The Winchesters also learn that "Brick" was actually a Mayan athlete who had made a deal with an ancient god to live forever and excel at various sports under different aliases over the centuries in exchange for sacrifices of human hearts each year. When Brick fell in love with a mortal woman (Patty McCormack) in the 1940s, they stayed together even after she became so old she had to pose as his mother. Eventually, he committed suicide because he couldn't stand the thought of living without her. The recipients of his organs enjoy the power they are suddenly bestowed with and are eager to carry out the murders to fulfill Brick's deal with the god. Brick's wife tells the brothers that they must destroy Brick's heart to end the murders. Upon tracking down the woman who received Brick's heart (Kyra Zagorsky), Sam and Dean stab her in the heart, sparking a chain reaction that results in the deaths of not only the woman but also the recipients of Brick's other organs. Meanwhile, Sam contemplates returning to normal life after they have sealed the gates of Hell, though Dean, having come to re-embrace and enjoy the violence of hunting while in Purgatory, refuses to entertain the notion and wants to keep hunting with Sam.
Source: Wikipedia
Source: Wikipedia