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 ::
4.21 Beginning: Great shot of the devil's trap vent in the panic room ceiling to open the episode.
Of course, Sam is still locked inside, after calling for Dean and pounding on the door in vain.
4.21 Ending: By episode's end Sam & Dean have had a horrible fight and Sam walks out the door, leaving a broken and defeated Dean all alone.
Sam: You don't know me. You never did. And you never will.
Dean: You walk out that door, don't you ever come back.