It stars Reed Birney, Ann Dowd, Jason Isaacs, and Martha Plimpton as grieving parents who meet to discuss a tragedy involving their sons.

Jay and Gail Perry are parents grieving the death of their son Evan, a victim of a high school shooting.

The couples had met previously, in which Jay and Gail made hurtful comments toward Richard and Linda when they were all going through the public legal procedures that resulted from the incident.

Richard and Linda tell that they knew that he became more depressed due to their family moving houses, lack of friends, and bullying at school.

While acknowledging that Hayden's schools and therapists did not respond appropriately to their findings, Richard and Linda express their guilt and regret over how their failure to see and react to any signs that their son could have become violent.

In November 2019, it was announced that Fran Kranz would write and direct Mass in his feature directorial debut, with Reed Birney, Ann Dowd, Jason Isaacs, and Martha Plimpton attached to star.

The site's critics consensus reads, "Mass requires a lot of its audience, but rewards that emotional labor with a raw look at grief that establishes writer-director Fran Kranz as a filmmaker of tremendous promise.

"[25] Writing for Little White Lies, Hannah Strong summarized the film as a "study of human pain and anger in painstaking detail, supported by a script which is hauntingly realistic without dipping into mawkish or exploitative territory.

"[26] Owen Gleiberman, from Variety, said the film "announces Fran Kranz as a bold new filmmaker who has earned the right to excavate a subject as sensitive as this one.

"[29] In his review for The Hollywood Reporter, David Rooney said the film was "a harrowing watch, but a cathartic one, with each of the four superb principal actors delivering scenes of wrenching release.

"[30] Furthermore, Vox journalist Alissa Wilkinson said Mass "leaves plenty of breathing room for characters to have authentic moments of emotion and puts a gentle, grace-filled frame around an almost unspeakable tragedy.