In post-civil war Johnstown Valley, PA, a headstrong young woman, grieving the death of her only child, struggles to save her marriage to an embittered, volatile factory worker, while a rapidly deteriorating dam threatens to destroy the town. Based on true events. 

SYNOPSIS:

Johnstown, PA. 1889. Following the death of their daughter in a diphtheria epidemic, LAURA FLANNERY finds her marriage crumbling. Instead of offering solace, her husband PATRICK has grown increasingly distant, lost in a morass of guilt, bitterness and shame. While Laura attempts to re-purpose her grief into a book she is furtively writing, the haunted Patrick dulls his pain with drink and tries to organize his fellow mill workers to strike against the hated owners.

Meanwhile, Patrick’s employer, steel titan DANIEL MORRELL, tries to warn his fellow members of the South Fork Club, a mountaintop summer retreat for the privileged wealthy: Based on an engineer’s assessment, the dam overlooking the valley has fallen into terrible disrepair. One serious rain could burst it, sending the river rushing into the towns below, spelling disaster for the factory workers and their families living there. The aristocratic and arrogant board members blithely dismiss the warnings.

Laura works as a server at a South Fork Club function. There, she unexpectedly sees EDWARD BIDWELL, scion of a wealthy Pittsburgh mining family, with whom Laura had a brief but passionate relationship before he went to study in Europe. He has kept his flame for her alive and written longing letters she has had to hide from Patrick. She is resolved to let the past lie but Edward clearly is not.

A drunken Patrick discovers a gift that Edward had given Laura, and an ugly fight breaks out between them. When Patrick’s rage explodes into physical violence, Laura leaves him. She runs to Edward, who is more than happy to provide shelter in his family’s summer cottage at South Fork. Edward accompanies her to the cemetery to visit her daughter’s forlorn, neglected grave – something Patrick, out of guilt and shame, had refused to do.

When Edward’s father, the imperious mining tycoon THEO BIDWELL, returns to his summer home and finds Laura – whom he recognizes as a server from the club – staying there, he confronts his son and threatens to discontinue supporting his wayward lifestyle.

Patrick, meanwhile, accepts a promotion at Morrell’s steel factory, abandoning his friends and co-workers (who have been infiltrated by a Pinkerton detective, BANDY) to an ill-fated strike that turns violent and deadly. Abandoned by Laura and a pariah amongst his fellow factory workers, Patrick’s mood darkens as his thoughts turn to retribution. First, he tracks down Bandy and beats him nearly to death.

Then, amidst a violent, drenching rainstorm that has sent everyone scrambling to higher ground, Patrick heads to South Fork, armed and looking to kill both Edward and Morrell, whom he believes cheated his father of his rightful share of an invention.

Meanwhile, Bidwell Sr., eager to separate Laura from his son, tells her about the deadly labor strike, and arranges a carriage to take her back to the valley. Before she leaves, Edward tells her of another gift he has for her, which she will receive at a later date.

Back in the valley, she finds the streets flooded and growing concern that the South Fork dam will burst. With no sign of Patrick, she hides in an attic with several women, including her snobbish neighbor MRS. QUINN and her daughter EMMA.

At South Fork, Patrick finds the club deserted except for Morrell, and the two have a confrontation. Morrell, citing the impending danger of the dam giving way, convinces Patrick to put down his weapon and return with him to the valley to be with their families.

As they make their perilous way in a carriage, the weakening dam finally gives way, releasing a torrent of water that builds to an enormous wave, tearing down houses, uprooting trees and boulders, destroying bridges and carrying away trains. Train cars pile up against a stone aqueduct, then explode into a hellish inferno.

The house Laura is hiding in is demolished by the wave, and Laura is swept away. She awakens the next morning, clinging to a branch, to a hellscape of dead bodies, rotting animal carcasses, and piles of splintered lumber where homes once stood. She spends the night in the shell of a church, where she reunites with Emma. The two wander the wasted landscape until Laura discovers a tent that has been set up to house the dead. There she discovers Edward’s body, and realizes that he had returned to look for her.

Later, she sees Patrick, working as part of a volunteer crew. The two never speak, however, as she wordlessly blows him a kiss and walks away, a gesture his disconsolate father used when he deserted his family.

Months later, as the town is beginning its tentative rebuilding process, Laura and the orphaned Emma visit the cemetery so Laura can pay her respects to Edward. She also visits her daughter’s grave, which is now adorned with an elaborate headstone, Edward’s final gift to her.