is a novel by Sir Terry Pratchett, published in 1987. It is the fourth book in Pratchett’s hugely successful Discworld
series of humorous fantasies, and the first to focus on the recurring character of Death.
The story begins with Death in a room where hourglasses associated with every living person are stored. He selects one and takes it to a candle to see by, and begins a vision of the world, slowly narrowing it down to a field where a young boy is running. Death says a single word: Yes.
On Discworld, Mort is an awkward and unhappy apprentice to his family’s farm, and hopelessly fails at every aspect of it. His father Lezek gives in and takes Mort to the local hiring fair, hoping to find the boy another profession to pursue and happy to get his daydreaming son out of his hair. At first Mort seems destined to fail in this as well, but just before midnight Death himself appears and offers to make Mort his apprentice. Lezek mistakes Death for a normal undertaker, and Mort is allowed to take on the position.
Mort accompanies Death to his unearthly domain, and is introduced to Death’s servant Albert, an extremely old man, and Death’s adopted daughter Ysabell. Death informs Mort that his training will begin with him accompanying Death as he travels to collect the soul of a king scheduled to be assassinated by the Duke of Sto Helit. When they arrive, Mort impulsively tries to prevent the assassination, but fails miserably. Death is annoyed and informs Mort that deaths are predestined and cannot under any circumstances be avoided.
Mort continues his training, and eventually Death decides the time has come for Mort to retrieve a soul on his own. Mort is assigned the collection of Princess Keli’s soul; she is the daughter of the same king who was assassinated in Mort’s first experience with Death. Instead of killing Keli and taking her soul, Mort kills the assassin sent by the Duke. Although this spares Keli’s life, all the people in the castle and surrounding area begin acting strangely, as if something terrible and awful has happened that they simply can’t remember. Keli notices this behavior, and further notices that no one will acknowledge her existence unless she forces them to, and even then they seem to forget she is there immediately after.
Princess Keli meets a wizard, Igneous Cutwell. Because Cutwell is magically trained to see the invisible, he can perceive Keli, and she hires him to make the people see her again.
Mort discovers the consequences of his actions: He has created an alternate reality in which Keli lives, but this reality is unstable and is being consumed by the dominant reality. When this process is complete Keli will again be dead. Mort visits Cutwell to ask him about all this, and during this visit Mort sees a portrait of Alberto Malich, founder of the Unseen University (the school of wizardry in Discworld), and notices that he looks very much like Death’s servant, Albert.
Back in Death’s domain, Mort asks Ysabell for help investigating Albert. She takes him to the Stack, a huge library holding the biography of every person. They confirm he and Alberto are one and the same; Alberto Malich had attempted to perform a ritual to keep Death away from him, but the spell malfunctioned and sent him directly to Death. He chose to remain with Death in order to forestall his own demise.
Death, believing Mort capable of handling his duties, takes a holiday and travels to the city of Ankh-Morpork in order to experience mortal life. He drinks, gambles, and takes a job. Mort begins to look more and more like Death during this time, and even his personality begins to be overwritten with Death’s. Mort must go alone to collect the next souls on the list, both of whom are scheduled to die on the same evening that reality is destroyed. Mort forces Albert to give him a spell that will slow this process down. When Mort and Ysabell leave, Albert returns to the Unseen University and once again attempts to cast the spell to free him permanently from Death. The spell instead summons Death again—as well as the portion of Death that had been taking over Mort, reverting Mort to his old self. Death is unaware of Albert’s actions and takes him back as a servant.
Mort and Ysabell go to Princess Keli as she is about to be crowned Queen, which Keli hopes will prevent the destruction of reality. This fails, but Mort saves Keli and Cutwell when reality collapses and brings them to Death’s domain. Death is waiting for them, having discovered what’s been happening. Angered, Death fires Mort and starts to take Keli and Cutwell’s souls, but Mort challenges him to a duel for them. Death defeats Mort, but is impressed and decides not to kill him, sending him back to Discworld instead. Death then has reality changed, making Keli the ruler of her kingdom. Mort and Ysabell get married and are created Duke and Duchess of Sto Helit by Queen Keli. Death attends the reception, and gives Mort the alternate reality he created, now the size of a tiny pearl.