The central conflict of Mercy is the case and trial of Jamie MacDonald, who confesses to killing his terminally ill wife, Maggie. Although the defense presents an insanity plea, and the prosecution asks for the terms “mercy” and “mercy killing” to be banned throughout the trial, it is clear that this is what Maggie’s death was. However, the case is ultimately argued along the lines of whether the circumstances surrounding Maggie’s condition are important or not when judging Jamie’s actions, and the book explores the topic of euthanasia.

Euthanasia is defined as “the practice of ending the life of a patient to limit the patient’s suffering” (“Euthanasia.” University of Missouri School of Medicine). The word is derived from the Greek terms “eu” (good) and “thanatos” (death), indicating the experience of a comfortable death for a patient who is terminally ill and thus experiencing a lesser quality of life. There are nuances to understanding euthanasia, including distinctions related to the manner of ending a life: Active euthanasia, such as injecting a lethal drug, or passive euthanasia, such withholding or withdrawing life support, are categorically different. Similarly, voluntary, involuntary, and non-voluntary euthanasia distinguish between whether euthanasia was administered with the patient’s consent or not.