"Carry on my wayward son, there'll be peace when you are done, lay your weary head to rest, don't you cry no more. . ." -- Kansas
So starts this episode, recapping all that started John Winchester on his quest to kill the demon that murdered his beloved Mary, leaving his four-year-old and six-month old sons motherless and dragged into the fight right along with John.
Meg walks into Pastor Jim's church and slits his throat, then later does the same to another Winchester friend and compatriot, Caleb. She informs John that she will kill all his friends and anyone who ever helped him until he gives her the Colt. He agrees, despite the fact that he, Dean and Sam know, thanks to one of Sam's vivid visions, that this very night, THE demon, the one who killed Mary and Jess, is going after another family, another mother and child, and they need the Colt to do away with it forever.
John desperately wants this quest to be over; he wants Sam to go to school, Dean to have a home, even if it means sacrificing himself in order to accomplish it. It's heartbreaking to see how tired he is, how determined to end the deaths and see his children free of chasing what he believes he has forced them to chase.
Upon learning of Sam's visions, John demands to know why Dean didn't tell him. Of course, Dean informs him, none too kindly, how many times they tried, including Sam's terrible phone call when Dean was dying. John apologizes, knowing how wrong he is in this instance. He decides to bring Meg a replica of the gun and send Sam and Dean to baby Rose's house with the real Colt to "Finish what I started."
The brothers have an angsty stakeout. They wish that they were with John, watching his back, and that John was with them, watching theirs. Sam thanks Dean for always having his back, which upsets the elder brother, who thinks it sounds like he's giving an â€œI'm going to dieâ€ speech, saying goodbye. "No one is dying tonight except the demon," says Dean firmly. Once it's GO time, lights going berserk, the brothers race into the house, where they are attacked by Dumb Husband Without a Clue. Sam gets a clean shot at the YED, but it somehow manages to disappear before the bullet finds its mark. Dean does grab Rosie from her crib seconds before it goes up in flames. As the family and the Winchesters gather on the lawn to watch the house go up, the husband is still making accusations, but his wife assures him these strangers saved their lives.
Sam sees the YED's dark figure standing in the flames upstairs in the nursery and wants to run up there and attempt to kill him again, fire be damned. Dean won't let him. Later, Sam is angry at him for not letting him end it, but Dean insists Mary and Jess' deaths are not worth dying over. Where once Dean angrily pushed Sam against a bridge for saying something similar, it's Sam's turn to do the same to Dean, except this time it's a wall. â€œWe're all we have!â€ cries Dean, in tears. This starts Sam crying a bit, too, and he releases his brother. Family is really all that's worth fighting for.
John does the best he can at the warehouse, but Meg's brother up and shoots her with the gun, proving it fake. She, of course, is horrified that he tested it out on her (nice sibling). John tries to get out of trouble by explaining he never used it before and had no idea it wouldn't work. He manages to escape them for a while, cleverly turning the water supply there into holy water, but Meg's brother corners and captures him, and when, later, someone finally answers John's phone, Meg tells Dean he's never going to see his father again. . .fadeout. . .to be continued. Oh, yeah, to one of the very best season finales of SUPERNATURAL ever!