The narrative unfolds through a series of flashbacks showcasing U.S. soldier Brandon Bartle [Alden Ehrenreich] and his experiences during the Iraq war alongside his friend Daniel "Murph" Murphy [Tye Sheridan]. Upon returning home to Richmond, Virginia, Bartle finds himself grappling with profound feelings of loss and guilt, having left Murph's fate shrouded in uncertainty. Their connection blossoms from the moment they meet in basic training, where Murph shares his aspirations to attend the University of Virginia, contrasting with Bartle's aimless, working-class background.
Before their deployment to Iraq, Bartle encounters Maureen Murphy [Jennifer Aniston], Murph's mother, who extracts a heart-wrenching promise from him: to deliver any news about her son personally, should the need arise. In Iraq, the duo encounters the stern leadership of Sergeant Sterling [Jack Huston], who is battling his demons. As they face the brutality of war, Murph's spirit begins to crumble. He develops an infatuation with Jenny, a compassionate medic, yet his fear holds him back from truly connecting with her. Tragedy strikes when Murph witnesses a bombing that severely injures Jenny, leading to an agonizing moment where he loses both her and his sense of safety.
Back home, Bartle grapples with the haunting shadows of PTSD and a fractured relationship with his mother, Amy [Toni Collette]. Following a heated confrontation, he finds himself wandering through the woods, where an impulsive decision nearly leads to his drowning in a river. Concerned locals alert the authorities, while Maureen, desperate for answers about her son, reaches out to Bartle, only to be met by Amy's tense hospitality.
As Bartle is discharged from police custody, he faces Captain Anderson [Jason Patric], who reveals the chilling news of Sterling's suicide and his ongoing investigation into Murph's disappearance. During his time in prison, Bartle is visited by Maureen, who urges him to share the truth about her son. With a heavy heart, Bartle recalls the tragic events that unfolded in Iraq, recounting how Murph wandered off during a mission and ultimately, how they discovered his lifeless body in a state that would break any mother's heart.
In a desperate bid to protect Maureen from the horror of the situation, Bartle and Sterling decide to dispose of Murph’s body in a river. As Bartle releases his friend into the water, he reflects on Murph's desire to vanish from the world, suggesting that perhaps this was the very escape he had yearned for. In an unexpected turn of events, Sterling commits an act of violence that rattles Bartle to his core.
With heavy emotions, Maureen seeks to find solace in Bartle's memories of her son. She implores him to reveal if there were any moments of joy amidst the turmoil. Bartle acknowledges there were, recounting a moment filled with tenderness when Murph, nervous yet hopeful, wanted to dance with Jenny. In a poignant climax, the film concludes with a beautiful image of Murph and Jenny sharing a slow dance, a bittersweet reminder of fleeting happiness even in the darkest of times.
