Dr. Nathaniel Grant is a pioneering organ-transplant surgeon who takes risks that other doctors would not in order to save the lives of his patients. He works closely with his ex-wife, Kate Armstrong, an organ-donor coordinator with whom he has a volatile relationship. Grant's arrogance and willingness to perform risky procedures causes him to butt heads with the hospital administration. But his main focus is on his intense relationship with his job and his patients, often at the expense of his family..