In a small South Korean village, the life of a single mother turns upside down when she discovers a mysterious connection to an ancient tunnel that leads to a parallel world. The protagonist, Ji Soo, is a woman in her thirties struggling to provide for her son, Dong Wook, while facing the economic and social pressures of everyday life. Her monotonous routine is disrupted when, after a series of strange events, she finds a hidden entrance in the forest that takes her to a place where time and reality do not function as they do in her world.
In this new environment, Ji Soo discovers that she has the opportunity to change past decisions and confront mistakes that have shaped her. As she explores this mysterious world, she encounters versions of herself and the people around her, allowing her to question her identity and the path she has taken. However, every choice she makes in this alternate universe has consequences both in her current life and in her relationship with Dong Wook.
Bearing the weight of motherhood, the longing for a better life, and the fear of losing what she loves, Ji Soo must choose between the comfort of her known life and the possibility of a new reality that could offer her what she has always dreamed of. This odyssey of self-discovery between fantasy and reality will lead her to redefine what it means to be a mother, confront her fears, and, above all, open herself to hope.