Season synopsis
Contains spoilers for this season and earlier seasons.
Sam Winchester leaves his plans for law school behind when his older brother Dean arrives with news that their father, John, has vanished on a hunt. The brothers cross the country following John's coordinates, taking jobs under false identities and investigating ghosts, monsters and demons along the way. Sam's visions and the clues John leaves keep drawing them toward the yellow-eyed demon responsible for the fire that killed their mother, Mary, and later Sam's girlfriend, Jessica.
After the brothers reunite with John, they retrieve the Colt, a gun said to kill supernatural creatures, and pursue the demon to Salvation, Iowa, where it is targeting a family with a baby. John draws Meg away with a decoy Colt and is captured. Sam and Dean turn to hunter Bobby Singer, trap Meg, and exorcise the demon possessing her; Meg's human body, already badly injured, dies after the spirit leaves. Her information leads the brothers to John's prison, where they rescue him and escape a building full of possessed hosts.
At a cabin, the Winchesters prepare for the yellow-eyed demon's arrival. Dean realizes the rescued John is possessed and refuses to hand him the Colt; Sam sides with Dean, and the demon reveals itself. John briefly breaks through the possession, allowing Sam to shoot him in the leg and force the demon out. The demon escapes, leaving the family alive but battered. As they drive toward a hospital, a demon-driven truck slams into the Impala, and all three are left unconscious in the wreck, with their condition unresolved.