An immortal goblin cursed to live forever seeks a human bride to end his weary existence, but his plans unravel when he meets a high-spirited high school student who can see the sword protruding from his chest. Gong Yoo stars as the titular guardian, a 939-year-old warrior who has protected mortals for centuries while secretly longing for release from his eternal loneliness. His path collides with Ji Eun-tak, played by Kim Go-eun, a bright young woman destined to become the goblin's bride and finally bring his long-awaited death. Their growing connection is complicated by the arrival of a brooding grim reaper, portrayed by Lee Dong-wook, who shares a mysterious and tragic past with the goblin. Blending fantasy romance with sharp comedic banter and poignant melodrama, this sweeping tale explores themes of fate, sacrifice, and redemption against the backdrop of modern-day Seoul. As the two supernatural beings navigate their intertwined destinies, they discover that even the loneliest hearts can find unexpected warmth.