M.Y., contract killer and great hypochondriac, is to kill Eduardo Blaisten. His mysterious client remains in the shadows, but this doesn't worry Mr Y, who defines himself as a Kantian style assassin, killing scrupulously, with efficiency and elegance, while always respecting the privacy of his paymaster.There is just one small problem: Mr M.Y. is going to die that very day. In reality, he has been dying for many years. The fact is that Mr M.Y is afflicted with such a variety of illnesses that he has been at death's door almost since birth. Our hero continually compares himself to the most illustrious hypochondriacs from the history of literature and thought: Poe, Voltaire, Tolstoy, Moliere. This mission, his objective and his numerous attempts on Blaisten's life involve our hero in an in increasingly complex intrigue, as his imaginary symptoms frustrate his attempts at homicide.