Tyler Williams is a popular high school senior on the wrestling team. Outside of school, he parties with his friends and spends time with his girlfriend, Alexis Lopez, but is routinely pushed by his domineering father Ronald both physically and mentally to be better. His stepmother Catharine is more understanding of Tyler's pressures and tries her best to connect with him. Unbeknownst to anyone at school or home, Tyler suffers from a SLAP tear which he keeps secret from his family and team by stealing Ronald's painkillers. Tyler sees a doctor about this, who warns him of the severity of his injury and highly recommends undergoing surgery before it's too late. Unwilling to postpone the remainder of his season, Tyler continues to wrestle competitively until he is thrown onto his shoulder during a match, causing irreparable damage to his shoulder and ending his season, as well as his career.
One night, Tyler gets a text from Alexis, who reveals that her period is late. He takes her to get an abortion, but when confronted by pro-life protesters outside the clinic, Alexis contemplates bringing the child to term. This leads to a heated argument between her and Tyler, who objects to wanting to be a father at their age and in his condition. Angered by his insensitivity to her own feelings, Alexis walks home alone. Distraught, Tyler begins drinking heavily and abusing drugs at parties with his friends, and is later consoled by his younger sister Emily. Eventually, Tyler texts Alexis back, who is willing to mend their relationship. However, Alexis tells Tyler that she has decided to keep the child with support from her family. When Tyler tries calling her and demands to speak to her in person, Alexis breaks up with him and blocks his number, sending him into a rage in which he destroys his room and is grounded afterwards.
The night of the school dance, Tyler goes on Instagram and sees Alexis posing for a picture with friends, including Emily and another boy. He gets high and attempts to leave the house before being confronted by Catharine. Ronald attempts to diffuse the situation, but Tyler throws him to the floor and leaves in Ronald's truck. He drives to a house party where he sees Alexis go upstairs with the boy from the photo. Emily notices his arrival from a distance but says nothing. Tyler drinks heavily and then follows Alexis to the garage, demanding to know if she had sex with the boy and if she's been drinking while pregnant, though she asserts her friend is gay and that she was getting drinks for her other friends. Their argument turns physical, the two trading blows before Tyler strikes Alexis violently, slamming her head into the floor and knocking her unconscious as she begins to bleed out. Horrified, Tyler flees the scene and returns home before attempting to run away on foot before he is caught and arrested by the police. Paramedics attempt to resuscitate Alexis, but she dies from her injuries. Despite a guilty plea, Tyler is convicted to life in prison for second-degree murder and is eligible for parole after thirty years.
Between the flood of support Alexis receives and the spiteful messages levied toward her and her brother, a grieving Emily discontinues social media. She is then approached by Luke, an awkward but kindhearted classmate. He asks her out to lunch and the two begin a budding romance. During this time, Emily also overhears Ronald and Catharine arguing over Tyler, with Ronald blaming Catharine for her lack of presence in his and Emily's lives and Catharine blaming Ronald for his overbearing treatment of Tyler. Eventually, the two separate. One day, Ronald talks to Emily on a park bench and asks her if she's doing better. She says she is but feels guilty knowing that she could've stopped Tyler that night and that she hates him for what he did. Ronald advises her not to hold a grudge for his mistake and that no matter what, he loves them both. The two reconcile.
Meanwhile, Emily and Luke become closer, eventually having sex for the first time. Emily later soon learns from Luke that his estranged, abusive, cancer-stricken father is close to death. At her urging, the two drive to Columbia, Missouri so that Luke can make amends with him. Upon seeing him, Luke's father's spirits are lifted, and he begins to survive longer than expected. As Luke continues connecting with and caring for his father, Catharine contacts Emily over her whereabouts, though she struggles to find the right way to tell her before eventually saying that she's doing something important and that she appreciates everything she's ever done for her. Luke's father soon passes away in the night, and Emily consoles a mourning Luke on the drive home to Miami. Upon her return, Emily visits Tyler in prison, grieves with Alexis's parents, and connects with Ronald, putting herself at peace.