“Mommy said she’d come back with the rainy season!” “Wait for me. I’m on my way to be with you now.” Woo-jin lives alone with his young son, Ji-ho, since his wife, Soo-a, passed away a year ago. It breaks Woo-jin’s heart to watch Ji-ho who believes his mother’s promise to return with the rainy season, just like the story in a fairy-tale book. As summer comes and the rainy season begins, Ji-ho gets excited and takes Woo-jin into the forest. Woo-jin tries to console Ji-ho and tells him that his mother can’t come back, but Soo-a appears miraculously before them just as they are about to go. While Ji-ho is elated by his mother’s return, Woo-jin is baffled. And to their surprise, Soo-a has no memory of Woo-jin or Ji-ho. They take her home and show old photographs and videos that the family had taken together to help bring back Soo-a’s memory. When Soo-a asks about how they had fallen in love and gotten married, Woo-jin tells her stories from their high school years together. Meanwhile, Ji-ho wishes the rain will never stop falling so that his mother can stay, but the weather news predicts the rainy season will end in two weeks. Woo-jin is worried that Soo-a will vanish like the ending in the fairy-tale book. While cleaning up a bookshelf, Soo-a finds Woo-jin’s diary which contains the secret to her death. Soo-a realizes that she must leave once the rainy season is over, becomes sad, and prepares to part with her family as the three of them confirm their love for each other. When the rain comes to a stop and the sun comes out, Soo-a vanishes. As Woo-jin lives on with Ji-ho without Soo-a, he finds a letter she had written before she died. At last, Woo-jin learns the secret that Soo-a, who appeared at the start of the rainy season, had come from the past after seeing their married life in the future, and is not the same Soo-a who passed away a year ago.