We open on the town of Bedford Falls, where we hear prayers from all over town: all for George Bailey. "George is a good guy," says Ernie the cabbie. "Give him a break, God." (Already I'm tearing up a little - pull it together, Hudson!)
These prayers soar up to - heaven? It looks like outer space. God and St. Joseph are represented by star clusters, and they discuss the part that everyone remembers: George Bailey is about to kill himself, and Clarence Oddbody is the guardian angel who's got to stop him. What people might not remember is that Clarence is a bit of a screwup (he's been trying to earn his wings for two centuries!), and Joseph doesn't think they should entrust him with something as important as a man's life. Space God thinks Clarence's faith will see him through.
So they call over Clarence (represented by a tiny star), and he's happy for the opportunity. He's got an hour before George bites it, and he thinks the most important thing to do with that hour is to dress to blend in with the 1940s folks he'll be meeting. Joseph is like, "Seriously, dude? No, you're going to watch this movie of the life of George Bailey so you'll know how to deal with him when you do meet him. You're going to tell him you're a 200-year-old wingless angel anyway - may as well be dressed like a visitor from colonial Williamsburg while you're at it. No wonder you're still AS2."
(I like how Joseph is pretty much only in this scene, but you still get a sense of how exasperated he is with Clarence. Space God says pretty much the same thing, but he's much gentler about it.)
The screen goes dark: we're seeing from Clarence's point of view, and apparently the watching-movies-of-people's-lives power comes with having wings. Joseph, a little sarcastically, helps Clarence see, and gradually the picture comes into focus: George Bailey as a 12-year-old boy.
(on to Part 2)