The film centres on an aging 1970s rocker played by Pacino, who decides to turn his life around, and marks the directorial debut and career highlight of the "Crazy, Stupid Love" scriptwriter, reported Deadline.
"Every writer has 'that one project'... The one they feel so strongly about that they can't bear to turn it over to anyone else. For me, that project is 'Imagine'. It was a career highlight simply to get a script of mine into Al Pacino's hands. To have him read it, and then want to star in it... It's five steps past career highlight," Fogelman said.
"And now, to have Julianne Moore and Jeremy join the fray? It's beyond my wildest dreams. I've been hiding in my house for the past few weeks, out of fear that someone would pinch me. We are going to make a very special film here," he added.
The story kicks off when Pacino's character discovers an undelivered letter written to him when he has 19 by Beatles legend John Lennon.
The discovery causes him to rethink his life, shunning his lavish lifestyle and trophy girlfriend, and make up for lost time by reconnecting with the son (Jeremy Renner) he's never known.
Moore will play the owner of a small New Jersey hotel where the rocker takes up residence.
The film marks a darker turn for Fogelman, who has worked on several family-friendly animations in the past, including "Cars", "Bolt" and "Tangled".
Steve Carrell was originally attached to star in the project when it was first set up at Warner Bros Pictures.
