Susan Wheeler is the protagonist of the novel. She is an attractive 23-year-old third-year medical student working as a trainee at Boston Memorial Hospital. Susan, along with four other students — George, Harvey, Geoffrey, and Paul — takes rounds in surgery rooms and ICUs for making post-treatment notations on the health of patients. Mark Bellows, a surgery resident in the hospital, is the instructor and supervisor of this group.
The book is a journey into the inner workings of a hospital. As these students complete their three-month surgical rotation, the dilemmas and problems faced by a woman in a so-called "man's" profession are also highlighted. There are two patients, Nancy Greenly and Sean Berman, who mysteriously went into comas immediately after their operations. These incidents were attributed to complications within their surgeries due to anesthesia.
Nancy Greenly became comatose when her brain did not receive sufficient oxygen during surgery. Similarly, Sean Berman, a young man in his 30s in good physical condition, underwent a scheduled knee operation. Despite the operation's success, Sean failed to regain consciousness. Medically, the odds for such occurrences are one in 100,000, however, such odds seemed resolutely higher at the Boston Memorial Hospital.
Baffled by the comas of these two patients, Susan decides to investigate the mystery behind these peculiar events. She delves into the details on Nancy's medical history, occasionally skipping her lectures and missing rounds. After unraveling various details and facts relating to the case histories, Susan is led to the Jefferson Institute.
The institute is hailed as an intensive care facility designed to cut down on heavy medical costs. All patients who are declared brain dead or "vegetables" are referred to the institute. Here, she finds that bodies are suspended from the ceiling by wires in rooms walled by glass and are moved from room to room with little human involvement. This is where the "patients" are kept until a call for an organ comes in. Then the right donor is prepared, and the organ of choice is removed surgically (and without consent) and sold on the human organ market.
Susan also discovers that the complication of prolonged coma after anesthesia has been around 100 times more prevalent at Boston Memorial than the rest of the country in the past year. Shocked and aghast, Susan plans to discover more. She realizes that dressing up as a nurse leaves her free to roam about any part of the hospital and allow her to uncover more of the mystery.
Howard Stark, chief of the Department of Surgery at Boston Memorial, soon realizes that Susan now knows more than she ought. Subsequently, she is chased, shot at, and almost crushed by an oncoming train in the course of her investigation. Dr. Stark, frightened that the well-hidden, gruesome facts about the hospital may soon be revealed, decides to put Susan in a coma after an appendix operation. One by one, all the horrid deeds and organ-trading secrets of the hospital are uncovered.