Jun breaks the rules by sneaking a small, adorable dragon out of the Crystal Realm and bringing it home, but finds that her older brother, Eugene, has arrived and watches her every move.

Set 1,300 years after the events of How To Train Your Dragon, dragons are now just a legend to the modern world. When a geological anomaly opens up an immense, miles-deep fissure in the Earth’s surface, scientists from all over the world gather at a new research facility to study the mysterious phenomenon. Soon a group of misfit kids, brought to the site by their parents, uncover the truth about dragons and where they’ve been hiding -- a secret they must keep to themselves to protect what they’ve discovered.

The discovery of the Fire Realm poses a challenge as the Dragon Riders struggle to traverse it safely. Meanwhile, the unhinged Buzzsaw is on the lookout for a mysterious \"Lightning Bird\" making it harder to keep dragons a secret. Tom, Jun, D'Angelo and Alex face off against the most powerful dragon they've ever encountered in a high-stakes mission to save the Crystal Realm. And much to everyone's chagrin, Jun's pesky, nosey brother is coming uncomfortably close to learning what actually happens in Dragon Club.

The discovery of the Fire Realm poses a challenge as the Dragon Riders struggle to traverse it safely. Meanwhile, the unhinged Buzzsaw is on the lookout for a mysterious \"Lightning Bird\" making it harder to keep dragons a secret. Tom, Jun, D'Angelo and Alex face off against the most powerful dragon they've ever encountered in a high-stakes mission to save the Crystal Realm. And much to everyone's chagrin, Jun's pesky, nosey brother is coming uncomfortably close to learning what actually happens in Dragon Club.

在博克岛上居住着一个维京海盗的小部落。在这个部落中，力量和勇气是人们最为尊重的东西，因此，与龙的战斗时部落中男人的一种特殊而平常的生活方式。不…

故事的主人公是一个叫希卡普的维京少年，他住在博克岛，对抗巨龙是家常便饭的事。这个少年的思想很前卫，他另类的幽默感也不能讨好他的村落的村民和大家长。当希卡普被迫和其他的维京青少年——亚丝翠、鼻涕粗、鱼脚司，以及双胞胎暴芙那特和悍夫那特参加屠龙训练营，他就觉得这是他证明自己是个屠龙高手的好机会。但是当他遇到并结交了一只受伤的龙，他的人生就完全改变，而原本是希卡普证明自己的机会，却成为改变整个部落的未来的机会。片中另外一个重要角色是戈伯，他是村落的铁匠和驯龙训练营教官，只有他看出希卡普的潜力。

京岛国的少年小嗝嗝是部落统领伟大的斯托里克的儿子，他非常想像自己的父亲一样亲手屠龙——这些飞龙是岛上维京人放牧羊群的主要天敌——但他每次出现在部落屠龙的战斗中都只给大家徒增烦恼。在一次对抗飞龙的战斗中，希卡普偷偷用射龙器击伤了一只最神秘的“夜之怒龙”，并背着族人放生、豢养，甚至驯服了这只龙，还给它起名“无牙”。希卡普的神秘行径引起了一同训练屠龙技巧的女孩阿斯特丽德的怀疑。阿斯特丽德发现了希卡普的秘密，却同时被身骑“无牙”御风而飞的美妙体验所震撼。格雷决定在屠龙成人礼上向远征归来的斯托里克和族人讲明真相，说服大家放弃屠龙，却偏偏弄巧成拙，害得“无牙”被俘，一场更大的灾难就在眼前。

影片讲述小嗝嗝（梅森·泰晤士 Mason Thames 饰）偶然间遭遇传说中的夜煞没牙仔，并由此与之建立深厚友谊，进而打破两大族群间的隔阂，携手寻求和平的故事。

经过两集故事的历练和战斗中的成长，小嗝嗝（杰伊·巴鲁切尔配音／中文配音刘昊然）已然长大并成为了统领伯克岛的酋长。他与女友阿丝翠德（亚美莉卡·费…

曾经“不谙世事”的小嗝嗝(杰伊·巴鲁切尔)如今已经长大成人。他和飞龙“没牙仔”的生活也同样在一同的成长中，展开了一场全新的冒险旅程。这一次，他们…