Two top New York neurosurgeons, Dr. Hanson and his protégé, Dr. Jonathan Seger, explore the mysteries of the brain as they perform life-saving brain surgeries. A tumor is discovered in the brain of a young teen -- Dr. Hanson wants to operate right away, but the girl's mother is hesitant to allow him to do so.
Dr. Hanson takes a blunt approach to telling his patient, Kate Larson, that performing radiation on her brain tumor will most likely kill her unborn child. Upon hearing this, Kate refuses to undergo radiation, but agrees to a complex brain surgery.
A woman Hanson operated on three years ago returns after suffering from double vision. Tests show that she has had another aneurysm and only has a 20% chance of survival. Despite the odds, the woman agrees to be operated on, but her brother does all he can to stop it.
While celebrating his return from Iraq with his fiancé, Clay Harper suffers a stroke. Hanson and Seger debate how to treat Harper: Hanson focuses on the medical facs while Seger argues that his recovery will depend on support from Cindy. Meanwhile, the doctors treat Tilly Bates, an older woman with a brain tumor that has affected her personality.
When Erica Lund's seizures escalate in severity, Hanson tells her he needs to operate, but she refuses because she claims she sees God in the moments before the seizure strikes. Meanwhile, another patient being treated for a severe head wound that causes him to blurt out his deepest, most intimate thoughts.
After a teenager crashes on his motorcycle, he starts an emotional war between his severe mother and Goth girlfriend that trickles over to the hospital staff; hospital assistant Eddie fears the worst after an MRI scan.
Hanson's former mentor, Dr. Rosalind Halliday, asks him to perform a groundbreaking gene therapy procedure on one of her patients, but it soon becomes clear she isn't giving him the full picture.
Hanson and Seger try a radical surgical procedure to cure a man with depression. Holland works with a private physician on a patient who sees music as colors.