God talks to Moses through the burning bush, says go to Pharaoh and tell him "Let my people go!". Moses does that. Pharaoh says no. So God sends plagues. Moses says again, "Let my People go!". God hardens Pharaoh's heart so he says no again. So God can send more plagues.

I have to say, between this, Job, and the story of children being EATEN BY BEARS because they made fun of Elijah's bald head, God seems like kind of a prick.