Music has charms to soothe the savage Bart. And the angry Homer. And millions of Simpsons fans. Music has been crucial to The Simpsons from the start of its 25-year run, creator Matt Groening says.

After Bart’s old Internet cartoon, Angry Dad, is purchased by Herman Millwood, it is turned into a feature length movie with Bart heading up the project. Homer ends up being the voice and when the ...