故事描述必须赚钱谋生的少年，骑着摩托车，逢人就问需不需要帮忙，但总是得不到善意回应。后来好友找少年去自己家的鱼塭帮忙收成，收成结束需返还马达钥匙，好友父亲让他们一起送至邻村。然而到达时，少年发现钥匙不见了。面对已涨潮的海水，男孩说什么也要找到钥匙，因为这是他得到认可的难得机会。

15岁的政夫（佐久田修 饰）进城给生病的母亲买药，途中偶遇了表姐民子（山口百惠 饰），民子得知了姨妈阿菊的病情，主动请缨，要到政夫家里照料阿菊。就这样，两人以此为契机，交往变得密切起来，他们之间的关系也日渐亲密。时间久了，村里开始传起了有关两人的闲言碎语。某日，阿菊让政夫和民子去踩棉花，在此过程中，不慎踩空跌倒的两人顺势抱在了一起，压抑已久的感情终于爆发了。政夫将民子比作是野菊花，自己则是龙胆草，两个天真无邪的年轻人尽情的坦露着对彼此的爱意。政夫要提前回学校念书了，这意味着他将和民子分离，政夫在校期间，民子的家人将她许配给了一个民子并不爱的男人。

落魄作家为了写作素材，寻访到了一个叫做吴邪（鹿晗 饰）的古董铺子老板，而吴邪正准备离开这个城市，临走之前，吴邪和他讲诉了关于自己奇怪的盗墓家族往事，并说出了自己第一次随家族探险所经历的诡异事件：那一次他们的家族因为偶然获取了一件特殊的青铜器， 追根溯源，寻找到了被掩埋在中国西北盆地中的西王母古国，他们招募了一批盗墓贼一同前往古城遗址探险，进入了位于古城地下的西王母陵中，发现了当年周穆王于西王母求长生不死之术的真相。作家听完吴邪的故事，却发现其中有很多疑点，吴邪到底说的是自己的臆想，还是真相更加可怕复杂，因为吴邪的离开变成了永恒之谜。

Shipwreck survivors are found on Beiru Island (Infanto tô), which was previously used for atomic tests. The interior is amazingly free of radiation effects, and they believe that they were protected by a special juice that was given to them by the island's residents. A joint expedition of Rolisican and Japanese scientists explores Beiru and discovers many curious things, including two women only one foot (30 centimeters) high. Unscrupulous expedition leader Clark Nelson abducts the women and puts them in a vaudeville show. But their sweet singing contains a telepathic cry for help to Mothra, a gigantic moth that is worshiped as a deity by the island people. The giant monster heeds the call of the women and heads to Tokyo, wreaking destruction in its path.