As the Great Day of the Flyers nears, the Great Valley's flying youngsters are eager to participate in the annual exhibition to show off their skills. Everyone, that is, except free-spirited pterodactyl Petrie, whose individualism causes problems when it comes to staying in formation. Enter his dinosaur pals Littlefoot, Cera, Spike and Ducky, who encourage Petrie to embrace his uniqueness.

少年尤斯图斯的父母都是研究自然与环境的科学家，常年奔波在外，后来在一次考察中不幸遇难，留下的唯一遗物就是一盘他们临死前录制的录像带，指明事情跟一座诡异的城堡有关。为了查明事情的真相，尤斯图斯和他的两个小伙伴耗子成立了一个侦探组织，利用尤斯图斯在一次比赛中得到的奖金，开始了他们的探险之旅，在破解父母留下的暗示后，终于找到了这座神秘的城堡，随后在这里遇到了许多诡异的人和诡异的事情。