Zac Efron and Marcia Gay Harden are joining Paul Giamatti, Billy Bob Thornton and Jacki Weaver in the cast of “Parkland,” the producers announced on Wednesday.

Based on the epic book “Reclaiming History: The Assassination of President John F. Kennedy,” by the author and former prosecutor Vincent Bugliosi, the adapted screenplay is written by journalist and novelist Peter Landesman, who also will make his directorial debut here.

The book recounts the true story of the chaotic events that occurred at Parkland Hospital in Dallas on the day President John F. Kennedy was assassinated in 1963.

The film, to be shot in Austin, Tex., is destined for a 2013 U.S. theatrical release around the 50th anniversary of the assassination.

It will be produced by Playtone partners Tom Hanks and Gary Goetzman and Exclusive Media, who will also be financing.

“Zac Efron continues to impress us with his recent shift into more dramatic roles which showcase his exceptional acting skills, and Marcia Gay Harden is an unparalleled actress who gives tour de force performances in every film she appears," said Guy East and Nigel Sinclair, Exclusive Media’s co-chairmen, in a statement. "We look forward to seeing their combined talent in Peter Landesman’s powerful and mesmerizing story alongside the excellent cast already attached to this film.”