I’ve seen a unicorn rip a man’s guts out, an axe chop a man’s toes off, and an eyeball skewered on a sharp metal tent peg. It’s Sundance, and I’ve seen some shit. And yet nothing prepared me to watch Mass, a movie about four middle aged adults sitting around a folding table in a church rental space.

It’s hard to say who’s more reluctant to be there – Richard (Reed Birney) and Linda (Ann Dowd), or Jay (Jason Isaacs) and Gail (Martha Plimpton). Richard and Linda’s son killed Jay and Gail’s in a school shooter incident years ago, and this is an attempt for healing, or closure, or something other than the smothering pain they’ve been living in.

One room, 4 people, 110 minutes of emotionally exhausting confrontation, conversation, and contemplative silence. A movie like this either succeeds or it doesn’t based on two things: the script, and the performances.

The script, by director Fran Kranz, is restrained, nimble, as revealing as it is concealing. It’s almost voyeuristic to sit in on such an intimate and fraught conversation, but while we think we know where the lines will be drawn, Kranz shows the grief, victimhood, and aftermath of a mass school shooting is as complex as the event itself. It is natural to want to identify causes and assign blame, but here, in this room, guilt and innocence overlap.

Kranz is himself an actor with an intuitive sense of how dialogue can rise and fall, and how grief can express itself in more than just words. In this claustrophobic space, all four performances are committed; there is trauma and sorrow on both sides of the table. Each has lost a son. But Jay and Gail persist. They want, nay, they need to know: did Richard and Linda see this coming? Is there something they could and should have done? There isn’t going to be an easy answer here, just pain across four faces. Recrimination, bitterness, anger, empathy, and loss. There are heavy burdens in this room and perhaps Kranz is a little inclined to tidy them up by the end, but grief isn’t something you fix or get over. It’s something you learn to live with – the question is, will this conversation help them do so, and if not, can anything?