Michael Shannon's directorial debut Eric LaRue isn't a ghost story, but it feels like one.

Eric (Nation Sage Henrikson) is absent from much of the film, yet his presence haunts every scene. It haunts his mother Janice (Judy Greer) as she folds his clothes to give away. It haunts his father Ron (Alexander Skarsgård) as he reminisces on past father-son vacations. But they know — and we know — that Eric isn't dead. He's in prison for the murder of three of his classmates.

Eric's act of violence is not the focus of Eric LaRue. Instead, Shannon and screenwriter Brett Neveu (who also wrote the play on which the film is based) examine the aftermath of Eric's crime, especially his parents' differing attempts to process what their son has done. What follows is an aching exploration of grief and religion, all anchored by a stunning performance from the always-great, often-underused Greer.

Eric LaRue presents two very different ways to process grief via religion.

In the time since Eric shot three of his classmates, his parents have taken different paths when it comes to healing. Janice has isolated herself, but her discussions with her Presbyterian pastor Calhan (Paul Sparks) have convinced her to take some steps forward, like returning to work. Ron's approach also involves religion, albeit at a different church. He goes to Redeemer, where he is anointed by pastor Verne (Tracy Letts) and attends prayer groups with his beautiful, bubbly coworker Lisa Graff (Alison Pill).

Ron's time at Redeemer has made him optimistic, seemingly joyful, even. He tells Janice that prayer can heal any trial, and encourages Janice to let Jesus take her burdens from her forever. Janice doesn't want to let go, caught up in her own complicated feelings. Even though he isn't dead, the son she knew is gone. Is she allowed to mourn in her own way, even in the face of what he's done? Or is she to blame for his actions?

Her journey towards far-off closure begins with Calhan's suggestion that he facilitate a meeting between her and the mothers of the dead boys. Calhan means well, attempting to get Janice to talk over card games and supermarket banter. However, he's not remotely equipped to handle the emotion once these grieving women come face to face.

Calhan's meeting is a source of tension between Janice and Ron, who wants Janice to attend a similar meeting presided over by Verne. Where Calhan is soft, Verne is more of a hard-line preacher. In a menacing scene, he uses scripture to tell Ron to control Janice. From there, the conflict between the two parents only grows — a change Shannon often showcases effectively by framing Janice and Ron in different rooms in the same shot.

Judy Greer leads a tremendous cast with her own outstanding performance.

Greer has always been a talented actor, often taking on comedic roles or side characters. With Eric LaRue, it is so satisfying to watch her take on such a demanding lead. As Janice, she is at her most raw and most devastating, especially in scenes when she meets with the mothers of the dead students. Later, when she visits Eric and tries to drag some impossible answer out of him, she heads into darker territory with devastating naturalness.

Skarsgård and Pill also turn in great work, with Skarsgård getting some uneasy laughs from Ron's penchants for offering neck massages and Pill transforming Lisa's religious fervor into something almost terrifying. Their scenes together simmer with uncomfortable chemistry, as well as their joint obsession over their experience with Redeemer. Filling out Eric LaRue's cast of religious characters are Letts and Sparks as two sides of the same coin: one chilling but assuring, the other supportive yet out of his depth.

The play Eric LaRue was originally staged in 2002, but in the years since, its portrayal of a town in the wake of a school shooting has gained even more relevance. So too have its links between the reaction to the shooting and religion, which calls to mind the oft-repeated refrain of "thoughts and prayers" that follows every act of gun violence.

Shannon and Neveu don't focus on the larger political implications of Eric's crime, nor do they necessarily answer the tough questions Eric LaRue lays out. What they do do, however, is create a painful, intimate, and thought-provoking portrait of a deeply hurting couple. And in assembling such a stellar cast led by the remarkable Greer, they've embodied that portrait onscreen to the fullest.

Eric LaRue was reviewed out of its world premiere at the Tribeca Film Festival. It is currently seeking distribution.