静谧的夜空上，皎洁的圆月中住着全身洁白、似乎只有儿童才能看见的月亮先生（Katharina Thalbach 配音）。他蜷缩在方寸之间，孤独寂寞。某晚，一颗剧烈燃烧的小行星朝地球飞去，月亮先生趁机抓住火舌，随之坠落地球。与此同时，地球大总统（Ulrich Tukur 配音）正在一座天文台举行征服地球每一寸角落的庆祝仪式，小行星的到来令他倍感紧张，随后燃起征服月球的野心，为此他拜托沉寂许久的天才博士本森·真·黑暗博士（Thomas Kästner 配音）发明飞向外太空的火箭。月亮先生消失了，孩子们失望得睡不着觉。地球上始料未及的旅程，他将经历到什么呢？ 本片根据汤米·温格尔的同名畅销绘本改编。

The classic and beloved story from Dr. Seuss is now a CG animated film from 20th Century Fox Animation, the makers of the Ice Age films. An imaginative elephant named Horton (Jim Carrey) hears a faint cry for help coming from a tiny speck of dust floating through the air. Horton suspects there may be life on that speck and despite a surrounding community, which thinks he has lost his mind, he is determined to save the tiny particle! Jim Carrey and Steve Carell lead an all-star cast in bringing this wonderful family picture to life!