The film is film is about the last few years of Beach Boys drummer Dennis Wilsonâ€™s life.
Moretz would play Wilsonâ€™s daughter Jennifer and Grint will play Stan Shapiro, a mail room intern who became friends of Wilson.
The young stars will join actors Aaron Eckhart as Wilson and Vera Farmiga as Fleetwood Mac singer Christine McVie.
The film is going to be directed by Randall Miller. Production on the indie flick will begin on June 15th this summer.