When Tommy Fuller is sent home from church early for misbehaving, he discovers that his father has been helping escaped slaves make their way north on the Underground Railroad. In spite of the danger involved, Tommy assists his father and makes a new friend. A young slave his own age explains to Tommy that his family is seeking freedom by following the "drinking gourd", also known as the Big Dipper. Tommy bravely protects this family so that they will not be recaptured. He also grows in respect for his father, who is taking great risks to help other human beings. This book illustrates well the concept of civil disobedience for beginning readers.