JIM GAFFIGAN and Olivia Thirlby have joined Jason Clarke and Kate Mara in “Chappaquiddick,” the Ted Kennedy drama being directed by John Curran.

    Ed Helms and Bruce Dern are already on board the Apex Entertainment project that will begin principal photography Sept. 7 in Boston. Sierra/Affinity has come on board to oversee international sales of the project.

    The script tackles what some have described as the seven most dramatic days of Kennedy’s life: On the eve of the Apollo 11 moon landing, the senator becomes entangled in a tragic car accident on Chappaquiddick Island in Massachusetts that results in the death of former Robert Kennedy campaign worker Mary Jo Kopechne. The senator struggles to follow his own moral compass and simultaneously protect his family’s legacy, all while trying to keep his own political ambitions alive.

    Clarke is playing Kennedy and Mara will portray Kopechne.

    Gaffigan will play District Attorney Paul Markham and Thirlby will play a member of the so-called “boiler room girls,” a group of single women who attended the party on Chappaquiddick preceding the accident.

    The script, which was on the 2015 Black List, was written by Taylor Allen and Andrew Logan.(SD-Agencies)