After the loss of her father, young Thea has lived a secluded life without any friends, except for one. Her imaginary friend, Max, is a cause for concern for Thea's mother, who drastically intervenes with Thea's solitary social life. As a result, Max finds himself competing for Thea's attention, and his own existence.

In the unreal world of Sacred Heart Hospital, John "J.D." Dorian learns the ways of medicine, friendship and life.