At the beginning of the film, Lorenzo (played by Noah Banks and also Zack O'Malley Greenburg) is a bright and vibrant young boy living in the Comoros Islands, as his father Augusto (played by Nick Nolte) works for the World Bank and is stationed there. However, when his parents relocate to the United States, he begins to show neurological problems, such as loss of hearing, tantrums, etc. The boy is diagnosed as having adrenoleukodystrophy (ALD), which is fatal within two years. Failing to find a doctor capable of treating their son's rare disease, Augusto and his wife Michaela (Susan Sarandon) set out on a mission to find a treatment to save their child. In their quest, the Odones clash with doctors, scientists, and support groups, who are skeptical that anything could be done about ALD, much less by laypeople. But they persist, setting up camp in medical libraries, reviewing animal experiments, enlisting the aid of Professor Gus Nikolais (played by Peter Ustinov), badgering researchers, questioning top doctors all over the world, and even organizing an international symposium about the disease.
Despite research dead-ends, the horror of watching their son's health decline, and being surrounded by skeptics (including the coordinators of the support group they attend), they persist until they finally hit upon a therapy involving adding a certain kind of oil (actually containing two specific long chain fatty acids, isolated from rapeseed [canola] oil and olive oil) to their son's diet. They contact over 100 firms around the world until they find an elderly British chemist (Don Suddaby, who plays himself in a cameo role) working for Croda International who is willing to take on the challenge of distilling the proper formula. The oil, erucic acid, proves successful in normalizing the accumulation of the very long chain fatty acids in the brain that had been causing their son's steady decline, thereby halting the progression of the