What is it like to have power over life and death, and yet to struggle with your own humanity? Dr. Henry Marsh is one of England's foremost brain surgeons, a pioneer in his field and respected throughout the world. Surprisingly modest despite all his achievements, he still rides an old bicycle to work and worries constantly about his patients and the potential damage of such delicate surgery. "When push comes to shove we can afford to lose an arm or a leg, but . . . if something goes wrong [in brain surgery] I can destroy that person's character - forever," he says.

Marsh has been going to Ukraine's capital, Kyiv, for more than 17 years. Afflicted patients see him as a savior from the West; desperate parents travel great distances to bring him their children; and Marsh's Ukrainian colleague, Dr. Igor Kurilets, sees him as a benefactor and a mentor.  For all the satisfaction Marsh gets from going to Kyiv, once there he must confront a lack of trained staff, equipment and basic supplies, as well as patients grossly misdiagnosed or too late in finding him. Most haunting for Marsh are the children he can't save.