Carter Armstrong (Adam Rothenberg) and his younger brother Ellis (Ethan Peck) only have each other. They live in the mountains outside Albuquerque, New Mexico, in a trailer home. A discontent cabbie, Carter numbs his existence with alcohol while Ellis photographs the mountains around them. Their lonely lives are shattered when Ellis is diagnosed with acute leukemia, which can only be treated with a bone marrow transplant from a matching donor. After discovering Carter is not a match they decide to return to their childhood home in East Tennessee to find the abusive father from whom they fled many years earlier.
Their journey takes them through Texas where they meet Krystal (Mariah Carey), a local waitress who dreams of becoming a country singer. Fleeing her loveless marriage, Krystal takes pity on the weary brothers and agrees to drive them as far as Nashville. The trio embark on a fateful road trip - Carter and Ellis in search of a father who may be the only chance of saving the younger brother's life; and Krystal longing to fulfill her musical aspirations.
Along their journey, an emotional bond develops amongst the travelers as they cut across state lines, managing to elude Frank (Lance Reddick), Krystal's state trooper husband. Krystal becomes an unlikely guardian angel, watching over Ellis as she and Carter race him to Tennessee to get the care that he needs.
Once they reach Nashville, Ellis's condition continues to deteriorate and Carter is unable to locate their father. Carter's search takes him back through the places, people, and memories of his youth - his days as a star quarterback, his first love, his violent home life. As unforeseeable events unfold, Ellis's health becomes critical; Carter begins to make peace with his past; and Krystal pursues her musical career.