It's easy to find other reviews if you want to know what happens, but I prefer not to go looking for spoilers that way. The film focuses on a period when John is grappling with the knowledge that he’s dying and exploring different treatments for his cancer. He connects with someone in his support group who seems to be overcoming their illness through an unusual method, so John decides to try it too. However, this "miracle" might be more than it appears, and as things unfold, John and Amanda realize they may have misjudged the people involved, potentially leading to a dangerous situation that could cost John his life.

Source on TMDB