阿宽、沙虫和李静从小一起长大，但在小学毕业这一年，阿宽经历了人生中的第一个难关：三人行中的李静随父亲到厦门去打拚事业，而阿宽的爸爸因工作外派到台湾一年之后从此音讯全无、妈妈也为此患得重度忧郁症，在年仅十三岁的阿宽一肩挑起重担的这个夏天，他明白了这个世界注定都会像个过客一样抛弃他…… 从此阿宽和沙虫帮忙沙虫妈经营民宿，阿宽并兼任生态导览员的工作；李静随着母亲的事业再次回到这块她朝思暮想多年、有阿宽在的土地；钢琴少女小青受邀参加大酒店的开幕音乐会表演；大酒店的设计师许磊也将出席开幕宴会…，五个年轻人的相遇像是音符在乐谱上被谱好一般，爱情的旋律悄然响起。 交错复杂的感情曲线、牵扯不清的时代纠葛，飞越了两岸四地的跨海情缘和这个青春炽热的夏天，像被命运安排好的一样，同时相交于这座浪漫的金门岛屿………
AhKuan, ShaCong and LiJing grew up together, but the year of graduation from elementary school, AhKuan faced the first obstacle in his life: Out of the trio, LiJing will be going with her father to XiaMen for his job, and AhKuan's father was sent to Taiwan to work and has had heard no news from him ever since. AhKuan's mother thus has severe depression, and on this summer day, AhKuan who is only 13 years old has to take up this huge responsibility, he understands that this world will abandon him just like a traveller... From then on, AhKuan and ShaCong help ShaCong's mother to manage her bed&breakfast, AhKuan is also a wildlife tour guide; LiJing returns to the place that she has been thinking about for many years with her family, the place that has AhKuan. Pianist XiaoQing is invited to a big hotel's opening music performance; the hotel's designer XuLei will also be attending the opening... The 5 youths' meeting is just like the scores on an already-arranged music sheet, the tune of love silently starts playing. The complicated love relationships, intertwined with generational differences, cuts across the the different countries. And this warm young summer day, just like it was pre-arranged by fate, intertwines with the romantic JinMen Island.
