『恐竜博士』として子供たちの憧れの存在である牧野博士が星元市にやってきた！ 峠で見つかった新種の化石の調査のためらしい。
ユウマは自分も憧れていた博士にあえると喜ぶのだが、ヒロシは複雑な表情を浮かべる。実は博士はヒロシの恩師だった！ そんな中、一夜にして化石のあった場所が湖と化す現象が発生し…。
A favorite of kids far and wide, the Dinosaur Professor, Shinya Makino has arrived in Hoshimoto City. And it seems he wants to investigate the fossil discovered at the mountain ridge.
While Yuma is excited to see his childhood hero in action, Hiroshi seems troubled. As it turns out, the Professor was Hiroshi's teacher!
Among all this, a lake suddenly appears at the excavation site...
