Susan Sarandon and Pierce Brosnan's The Greatest screened twice over the weekend at Sundance, and however overcooked the dead-son weepie feels, we can't argue with multiple standing ovations.

Brosnan in particular, who plays the patriarch of a family devastated by the death of their teenage son in an automobile accident, was singled out for demonstration of audience affection, prompting those at Saturday morning's screening from their seats for an ovation that lasted maybe 15 seconds but felt like forever in the usually subdued early-morning setting. Sarandon and director Shana Feste felt the love as well, along with young co-stars Carey Mulligan, Johnny Simmons and Zoe Kravitz. We've been to a lot of public screenings over the years and seen and heard a lot of pushover audiences go nuts for film. This was one of those once- or twice-a-fest scenes where you could almost smell 600 people at the Racquet Club losing their shit. People love this movie.

But why? Brosnan (who also produced) is out of his depths as Allen Brewer, a mathematics professor maintaining his stiff upper lip while wife Grace (Sarandon) melts down completely following their son Bennett's fatal car wreck. Allen's determination to hold the family together is meant to reinforce his stone wall blocking grief, but in the presence of the more genuinely whacked Grace — who wakes up crying and spends months, in hopes of some closure, reading to the comatose driver who struck her son's car — it never feels like more than a high-stakes mourn-off punctuated by convenient expository fights, loving plunges into the ocean, etc.

It was a mindfuck for Sarandon, and the emotional imbalance shows in the parts of her performance not drugged within an inch of their life by Feste's potent script bromides.

"I have to admit that when I read it, it was so eccentric and there were a lot of things I didn't realize — until we actually started doing it —how difficult it was," she told the audience after the screening. "That was my bad. There are some actors who say they can never remember their real names when they're filming. I can never remember my character's name. When I go home to my kids, I completely leave it behind. I found on the days when we did some of the very, very emotional scenes that you have to hold on to for eight or 10 hours, my body chemistry actually changed. I was really shocked about how I smelled and the person I became. It was really horrible. That was the first time I realized that kind of impact when you imagine those things; your body can't tell the difference between what's imaginary and what's real."

So how did Sarandon and the others get through the 25-day shoot? "The cast was really, really fun and loving," she said. "It was a very happy set; sometimes I think we overcompensated. I think the two funniest sets I've ever been on were Dead Man Walking and Lorenzo's Oil. Explain that."

Yet there are two reasons to see The Greatest: Mulligan and Simmons, playing Bennett's pregnant girlfriend and messed-up little brother respectively, both extraordinary and nothing short of sincere in navigating the dynamics of their own grief. We'll get to this later today (and later this week in a little more depth), but Mulligan, whose Greatest and An Education performances had hype-within-the-hype momentum accompanying them before the festival even started, is an insanely vivid talent whose relationship with Allen Brewer is the only thing that salvages Brosnan's own performance; her retelling to him of meeting Bennett on their last day of school is devastating. At 23, and with little on her resume besides 2005's Pride and Prejudice and some British TV, she already improves everyone around her. Simmons, meanwhile, was also one of the only redeeming things about The Spirit, portraying the hero as a lovesick young man. His responsibility to parse his love/hate relationship with his mythologized brother refines that heartbreak here.

When — not if — The Greatest is bought (IFC Films execs, for starters, hovered excitedly outside the theater Saturday morning), it's destined to attract all the same gloom-fetish pushovers who got it up for Revolutionary Road and In The Bedroom before it. But here's hoping they recognize the actual best of it; it doesn't take much looking to find the real stars in all that pitch black.