Moses is guarding his father-in-law's flock of sheep, and he wanders with them "beyond the wilderness" (3:1) to Horeb, the mountain of God.
An angel of God appears to him in the form of a bush that's on fire but doesn't burn. Now that's a trick.
Moses checks out the situation, naturally.
God addresses Moses and tells him that he's back to help the Israelites out of bondage in Egypt. And guess what? Moses has to lead them.
Moses, a bit freaked out by all this, asks God why he's been chosen for the job.
God tells him not to worry, that he'll do all the heavy lifting. There'll be miraculous wonders, a new home for the Israelites ("a land flowing with milk and honey" [3:8]), and lots of shiny stuff for the Israelites ("You shall plunder the Egyptians" [3:22]).
God also reveals his name to Moses, and identifies himself as "the God of your ancestors."