Illustrator Xu Zhiyi accidentally discovers that her new neighbor across the hall is actually her first love, Gu Chenzhou. Behind their breakup on that rainy night four years ago lay hidden reasons, and numerous misunderstandings have piled up between them. Because of her niece Suisui, they interact frequently, gradually uncovering long-sealed past events. The two untie their long-standing emotional knots, let go of past barriers, and choose to run toward each other once again.