"The STEM Crew Kids Adventures: Building a Balloon-Powered Car" is a children's book about four STEM Crew Kids who are given an engineering project by their science teacher. The book follows the group as they work together to build a balloon-powered car and emphasizes the importance of teamwork, creativity, and problem-solving skills. The story also showcases the passion of one of the STEM Crew Kids, Ruth, for building and fixing gadgets and how her aunt, a mechanical engineer, encouraged her interest in engineering. Overall, the book encourages children to explore STEM fields and highlights the fun and rewarding aspects of working on a STEM project.