Ben Wolf goes for a sports physical and gets told that he has a rare blood disease and that he has less than a year to live. Ben decides not to tell anybody and to deny treatment. Since he's eighteen, the doctor is powerless to contradict him.
Then, Ben decides that he has to make the absolute most of the time that he has left. Since he doesn't yet actually feel sick, he decides to join the football team instead of continuing with the cross country that he has pursued throughout high school.
He decides to pursue a relationship with Dallas Suzuki, who is one of the smartest, prettiest seniors in his small-town Idaho school. He is surprised when she invites him to homecoming.
Ben takes on a controversial project for history class, despite his teacher threatening to fail him. Knowing that he won't be going to college anyway, he doesn't care.
Rudy McCoy, the reclusive town drunk, becomes Ben's newest and most unlikely friend, based largely on their shared interest in Malcolm X.
After Ben and his brother Cody secure victory for their team in the homecoming game, Ben goes to the dance with Dallas, after which he learns about a traumatic incident from her past. As they become closer, Ben begins to worry about how hurt Dallas will be after his death.
This is followed by another huge revelation from Dallas, and Ben misses his best chance to tell her that that he is dying.
Rudy reveals a shocking secret that Ben must work through: that he has a history of molesting children and has feelings of attraction towards Ben.
Rudy later ends his life, after leaving a note thanking Ben for his friendship and apologizing.
Finally, in stages, he tells his loved ones the truth, and on his last day, Dallas is lying next to him as he slips into unconsciousness.