I'll try to post these every other week day (Mon-Wed-Fri), but I make no guarantees. Sometimes there will be more than one cap for a beginning or ending of an episode. I'm also using my capper's discretion - meaning I'm choosing the most aesthetically pleasing image that we see first or last not always literally the first or last things we see. I'll explain this as we go along.
:: Click on images for the HQ versions ::
4.16 Beginning: This episode opens with what looks like a huge traffic accident, but in fact it's where an angel has been killed. Castiel arrives at the scene and says goodbye to his sister. Great shot of the angel's wings on the pavement as the police arrive.
Our first views of the boys is as they're driving (from Pamela's funeral) and Dean wakes up feeling guilty about losing another friend. Dean's tired and Sam tells him to get angry.
4.16 Ending: By episode's end Alastair and Uriel are dead and Dean is broken in a hospital bed, having found out he was the one who broke the first seal in hell. It's a heartbreaking scene as he learns more from Castiel of what is expected of him and a tearful Dean admits he's not the same since hell and that he can't help.
Castiel: It's not blame that falls on you, Dean, it's fate. The righteous man who begins it is the only one who can finish it. You have to stop it.
Dean: Lucifer? The Apocalypse? What does that mean? Hey! Don't you go disappearing on me, you son of a bitch. What does that mean!
Castiel: I don't know.
Castiel: I don't. Dean, they don't tell me much. I know our fate rests with you.
Dean: Well, then you guys are screwed. I can't do it, Cas. It's too big. Alastair was right. I'm not all here. I'm not—I'm not strong enough. Well, I guess I'm not the man either of our dads wanted me to be. Find someone else. It's not me.