Adam Lerner, portrayed by Joseph Gordon-Levitt, is a 27-year-old public radio journalist living in Seattle with his artist girlfriend, Rachael. Despite the disapproval of his best friend and co-worker, Kyle, played by Seth Rogen, Adam is content in his relationship. However, he faces unexpected challenges when he begins experiencing consistent back pain, which Kyle jokingly attributes to unusual sexual positions. To put his mind at ease, Adam visits the doctor, leading to a life-altering diagnosis: he has Schwannoma Neurofibrosarcoma, a rare malignant tumor that requires chemotherapy.
Informed by his research that he has a fifty-fifty chance of survival, Adam struggles with the weight of this news. When he confides in Rachael, she reassures him of her unwavering support throughout this trying time. Meanwhile, Kyle initially reacts with shock but quickly tries to maintain optimism, urging Adam to focus on the possibility of survival.
Complications arise as Adam's overprotective mother, Diane, played by Anjelica Huston, wishfully tries to care for him, but he prefers the promise of support from Rachael instead. Seeking comfort, Rachael gets Adam a retired racing dog, highlighting her understanding of the therapeutic joys of pet companionship. However, her discomfort with hospital visits during Adam's chemotherapy creates a rift.
Amidst his treatments, Adam begins sessions with a young and somewhat inexperienced therapist, Katherine McKay. Initially skeptical of her abilities since she is not yet a doctor and is still training, Adam slowly opens up about his struggles. Their connection deepens, blurring the lines between therapist and friend, leading Adam to understand the emotional toll his illness takes on his loved ones, particularly his mother.
During his time in treatment, Adam also bonds with fellow patients, Alan and Mitch, whose candid discussions about the brutal realities of cancer provide him with both comfort and laughter. Though Adam tries to convince his new friends that Rachael is supportive, her tardiness on the day they wish to meet raises doubts among them.
As the story unfolds, Kyle keeps trying to uplift Adam's spirits, even suggesting cheeky ways to use his illness to connect with women. Eventually, the strain on Adam's and Rachael's relationship culminates in a painful breakup, as she admits that the stress of his illness has taken its toll on her as well.
The narrative takes a darker turn when Mitch's sudden passing amplifies Adam's fears. In his battle against the disease, he finds himself faced with the prospect of risky surgery, leading to an emotional confrontation with Kyle. Adam reaches out to Katherine, revealing his vulnerabilities, before discovering a heartfelt book filled with notes written by Kyle, demonstrating his genuine care for Adam.
As Adam prepares for what he fears might be his final moments, he reconciles with his family and friends. After a successful surgery, news arrives that the tumor was removed, offering a glimmer of hope for recovery.
In a renewed sense of optimism, Adam looks forward to a new beginning. As he prepares for a date, Kyle supports him while tending to his post-surgery incision. The doorbell rings, revealing Katherine, and with a smile, Adam signifies that despite the struggle, life continues.
