The film is a remake of the 2004 Japanese film with the same name, which is based on a novel by Takuji Ichikawa.
Soo-ah before she passed on, makes an unbelievable promise to her husband, Woo-jin
to return one year later at the start of the rainy season.
Miraculously, she keeps the promise and reappears before her husband and son, but she has no memory recollection. Sadly, the relief at their reunion is short-lived, because it turns out that Soo-ah has to leave her family at the end of the rainy season.