The first week in his new school, Thomas spends a lot of time thinking--about making new friends, being late to class, and getting his homework done. When his science teacher, Mr. Lunar, assigns each student a project on the solar system, Thomas begins to spend his time thinking and reading about the solar system. He knows that, in order to show what an excellent student he is, his will have to be a very special science project. While Thomas works on his project, he imagines vivid adventures for his sheep friends, who came to the rescue in his last academic escapade, Thomas's Sheep and the Great Geography Test. The sheep go to space camp, visit all the planets, and return just in time for the unveiling of what everyone agrees is the most spectacular science project ever.