How does an igneous rock turn into a metamorphic rock if the igneous rock came out of a volcano?

OKAY. Gah this is really annoying. So I have to write this creative story for science about the rock cycle. I start out with magma in a volcano and it coming out as lava. The lava cools and hardens and turns into an igneous rock, granite. How will it turn into a metamorphic rock? Where does it get the heat and pressure? Sorry for my ignorance, I'm just really annoyed haha.