With the accidental freeing of the fallen angel Lucifer in the climax of the previous season finale by Sam Winchester (Jared Padalecki), the Apocalypse has started. An unknown force whisks Sam and his brother Dean (Jensen Ackles) from the place that Lucifer has started his destructive rise, and transports them safely onto an airplane passing overhead. They seek information from the prophet Chuck Shurley (Rob Benedict), learning that their angelic ally Castiel (Misha Collins) has been killed for helping them, but he is unable to tell them much else because he is being watched by angels, who are working against the Winchesters to bring on the Apocalypse. Chuck later sends word through a fan of his work named Becky Rosen (Emily Perkins) that the angels have lost the sword of the archangel Michael—a weapon capable of defeating Lucifer—and gives them a cryptic clue as to its location. When Sam and Dean decode the clue, they are attacked by demons working for Lucifer, including their old enemy Meg Masters (Rachel Miner) and their now-possessed friend Bobby Singer (Jim Beaver). Bobby manages to overcome the demon long enough to stab himself with a demon-killing knife, severely wounding himself in the process. The Winchesters defeat the other demons, but Meg flees before they can kill her. The brothers take Bobby to the hospital, then set off to take Michael's sword before the demons do. They find the angel Zachariah (Kurt Fuller) at the place the sword is supposed to be, as Zachariah had purposefully planted the information that led them there in one of Chuck's prophetic visions. Zachariah explains that Dean is in fact Michael's "sword" as Michael's destined human host (called a "vessel"). However, Dean refuses to provide the permission required for Michael to possess him, even when Zachariah threatens to kill Sam and Bobby and tortures the brothers. Castiel soon appears and forces a frightened Zachariah to leave with the thinly-veiled suggestion that he has been miraculously revived (and Sam and Dean put on the plane) by God himself. He then hides Sam and Dean from angelic detection and disappears. Back at the hospital, Bobby is revealed to have been permanently paralyzed below the waist by spinal injuries from his having stabbed himself. Dean tries to bolster his friend's confidence by giving a stirring speech about beating both the angels and the demons, but admits to Sam in private that he believes that they are all doomed. He also admits that while he forgives Sam, he can't trust him anymore. Meanwhile, a man (Mark Pellegrino) whose family has been slaughtered by a killer begins having nightmares in which Lucifer appears to him in the form of his wife (Bellamy Young) and tries to convince him to let him take over his body so he can face God and seek justice. The man eventually agrees.
Source: Wikipedia
Source: Wikipedia