The narrative follows Claire Bennett (Jennifer Aniston), a former attorney grappling with overwhelming grief and chronic pain following a tragic car accident that resulted in the death of her son. Adding to her turmoil is the suicide of Nina Collins (Anna Kendrick), a member of her chronic pain support group. Nina's death, which occurred as she jumped at the intersection of highways 110 and 105, was shrouded in tragic irony. She landed on a flatbed truck transporting used furniture to Mexico, and her body went undiscovered until it had traveled 2,000 miles to Acapulco. A shocking return to the United States saw her remains sent back in a Rubbermaid cooler due to customs complications, further complicating her husband Roy's (Sam Worthington) grieving process as he could not claim her body for an entire week.
In the midst of her struggles, Claire is assisted by Silvana (Adriana Barraza), her devoted housekeeper, caretaker, and chauffeur, who tends to her numerous needs. However, Claire's ongoing anger and resentment lead to her removal from the support group after she refused to participate in a poignant exercise where members were asked to share their final words with Nina. Consequently, Claire's relationship with her husband Jason Bennett (Chris Messina) deteriorates significantly. Jason, overwhelmed by Claire's negativity, decides to leave, creating a chasm in their marriage.
Desperate for affection and companionship, Claire resorts to an inappropriate connection with the pool service technician, using him to satisfy her physical needs while also gifting him her deceased son’s toys, which he passes on to his own child. In a discovery of this secret, Silvana retrieves the toys and attempts to keep Claire grounded. Struggling with chronic back pain, Claire often seeks refuge in her pool, using it as a means to alleviate her suffering, although her nights remain restless due to her condition.
To appease her health professionals and maintain her prescription for painkillers, Claire is required to attend both support group meetings and water therapy sessions. Despite her efforts, six months pass without any improvement. The ongoing therapy leads doctors to suspect that Claire's pain is psychological rather than physical. When her medications are cut off, Claire becomes increasingly desperate.
One fateful day, Claire submerges herself in the pool with weights, seemingly attempting to end her life but ultimately resurfaces, symbolizing her constant battle between despair and the will to carry on. As the days go on, Claire’s life spirals, leading her to buy illicit drugs, feeding an addiction that trumps her desire for healing. Despite her external scars, she grapples with internal battles as well, haunted by vivid dreams and hallucinations of Nina.
Claire’s unwavering support system consists of Silvana, who remains loyal and protective. Since the accident, Claire's anxiety has made her uncomfortable in vehicles, leading Silvana to chauffeur her everywhere. Confronted with the reality of her situation, Claire finds herself visiting the highway where Nina took her life, seeking answers from a public security officer who recounts the tragic details of that day.
In her quest for clarity, Claire employs blackmail against Annette (Felicity Huffman), a member from her previous support group, to obtain Nina’s address, allowing her to befriend Nina's husband, Roy. The two share an unspoken bond forged through mutual loss and alienation, and together they pay a visit to Nina’s grave. Their connection deepens when Claire surprises him at his home, albeit briefly before succumbing to her drug cravings.
Claire’s dependencies lead her to traverse into Mexico for pain relief, as her American doctor refuses to refill her prescriptions. While Claire and Roy navigate their budding relationship, Claire holds Roy at arm’s length when he shows compassion regarding her accident, causing her to confront painful memories of her son. This tension escalates when they encounter Leonard (William H. Macy), the driver responsible for her son’s death, igniting Claire’s fury towards him. After an explosive confrontation, Claire's overdose prompts a hospital visit, where dreams of Nina ignite her guilt for not being able to fulfill her maternal roles.
Upon her discharge, Claire fights to remain free from drugs, seeking closure by revisiting the drive-in where she and Jason shared their first date. A moment of introspection leads her to the nearby railroad tracks where, through conversation with Nina, she acknowledges her capacity as a mother. Awakened by Silvana’s plea, Claire is called back to reality, revealing the toll her struggles have taken not only on herself but also on those around her.
In a twist of fate, an encounter with a young girl named Becky (Brittany Robertson) who attempts to steal from her unexpectedly leads to a meaningful act of kindness. Claire, moved by the experience, decides to bake a cake, serving as a heartfelt tribute to Nina while fostering a connection with Roy and his son during a birthday celebration. As Claire pays a visit to her son’s grave, Silvana honors the memory with a wind chime, embodying hope and healing. On the ride home, Claire embraces the possibility of renewal, symbolically choosing to sit upright in the car, suggesting a newfound determination to face life’s challenges head-on.
