In the final installment of the dystopian trilogy, the protagonist and his group of escaped Gladers are on their most dangerous mission yet. After surviving the treacherous mazes and battling the powerful organization WCKD, they now undertake a daring operation to rescue their friends who have been taken by WCKD. Their journey leads them to the Last City, a WCKD-controlled labyrinth that may turn out to be the deadliest maze of all. The protagonists must break into the city and navigate through complex obstacles, facing not only the city’s perils but also the resistance of WCKD's formidable forces.

Inside the Last City, the group uncovers unsettling secrets about the organization and their intentions. Meanwhile, tensions rise as the loyalties and intentions of their group's members are tested, with betrayal looming close. The stakes are high as the Gladers confront the truth behind the disease that has devastated the world and challenge the morality of using immune youths like themselves to find a cure. As they delve deeper, they must balance their need for revenge with the desperate hope for a way to save humanity.