In the story, Shin-chan and the Kasukabe Defence Group members were supposed to go to the B-class Gourmet Carnival. But, just then, a mysterious person asked Shin-chan to deliver a sauce to the carnival. But, that sauce was the only legendary sauce which could save B-class gourmet, which would otherwise get eradicated if fallen into the evil hands, and only A-class gourmet would remain. Will the mischievous kindergartener Shin-chan and his friends really be able to deliver the sauce safely to the carnival and save the world's B-grade cuisine?
小新與春日部防衛隊瞞著父母結伴到「B級美食嘉年華」吃「阿健的炒麵」。途中一名神秘女子託他們將「秘傳醬汁」送到阿健手中。偏偏一行人卻搭錯公車,困於深山。究竟,因「秘傳醬汁」而捲入A級美食機構邪惡計畫中的小新一行人,能否順利抵達嘉年華會場,吃到「醬汁的阿健」炒出的終極美味炒麵?