In a world where angels silently watch over humans, Seonghwa, an angel sent to observe the lives of mortals, is captivated by the vibrant spirit of Hongjoong, a passionate and determined young man who lives a life full of dreams and uncertainty. Seonghwa's mission is simple: to protect and guide, without ever becoming involved in the lives of those he watches. However, as he grows closer to Hongjoong, Seonghwa finds himself drawn to the warmth of his heart, the depth of his thoughts, and the beauty of his world-a world so different from the celestial realm Seonghwa knows.
Hongjoong, too, feels an inexplicable connection to Seonghwa, though he is unaware of Seonghwa's true nature. To him, Seonghwa is just a kind and mysterious stranger who always seems to be there when he needs support. But as their bond deepens into a romance that transcends the boundaries of mortal and divine, Seonghwa faces a dilemma-his fellow angels demand he return to the celestial realm, and the rules of his kind forbid such attachments. Meanwhile, Hongjoong struggles with his own feelings, unable to confess the truth to his human friends: that he has fallen for someone who isn't even supposed to exist in his world.
Caught between the pull of love and the weight of duty, Seonghwa must decide whether to defy the divine laws that govern his kind or to let go of the only love he's ever known. For Hongjoong, the truth about Seonghwa's nature will come crashing down, forcing him to choose between a life with a mortal's limitations or the impossible love that promises nothing but heartache.