The following version of the book was used to create this study guide: Gibbs, Stuart. Space Case. Simon and Schuster Books for Young Readers, New York, New York, 2014. Kindle AZW file.

Dashiell Gibson, known as Dash, is a twelve year-old who lives on the moon with his parents and younger sister, Violet, who is 6. His mother is geologist Rose Harris, and his father is mining specialist Steven Gibson. The family has been on the moon for about six months of their 3-year stay when the events of this novel take place. About two dozen people reside in the compound, along with a few who occasionally arrive for short periods of time, usually for specific purposes such as delivering food or providing some service. A maintenance worker named Garth Grisan and one family who paid for the privilege of spending a few months on the moon are also in the community. All the other families were chosen because of their areas of expertise, such as astrobiology or robotics. Many of these scientists have families and there are a few children who live in the small community. The community is called Moon Base Alpha, or MBA.

Dash opens by saying that living on the moon sounds like an incredible adventure, but that there are problems no one mentioned when the family was recruited for this task. The toilets are sometimes problematic and are located across the building from the residential area. The sleeping pods are small and the inhabitants often feel claustrophobic. Transporting actual furniture is overly expensive, meaning they sleep on air mattresses and sit on inflated chairs. The residents exist on dehydrated food that tastes terrible. Sometimes, the food makes Dash sick.

One night, Dash has to make the trek across the campus to the bathroom after one of the meals makes him ill. The toilets are complicated pieces of equipment and Dash's breaks before he is finished. While he is struggling to make the repairs, Dr. Ronald Holtz arrives. He is the doctor for the small community and is well-liked. Dash hears Dr. Holtz saying he plans to make a major announcement the following day and Dash is excited for any potential change in the sheer monotony of this life. However, he wakes the following morning to discover that Dr. Holtz left the buildings of the MBA and died on the moon's surface. Remembering that Dr. Holtz had seemed excited about his plans for an announcement, Dash immediately suspects foul play. The base commander, Nina Stack, tells Dash to stop talking about it. Nina knows there are some who want to shut down the program, and she is worried about all sorts of negative publicity, which would be worse if someone found out NASA had placed a murderer in their moon program.

One of the new arrivals to the base introduces herself as Zan Perfonic and she encourages Dash to help her solve the mystery of Dr. Holtz's death. Another new arrival is Kira Howard. She is Dash's age and soon becomes caught up in solving the mystery as well. Kira and Dash continue to follow the clues and soon discover that Dr. Holtz claimed to have discovered proof of intelligent life on other planets. Garth, the maintenance man, believes humans are not ready for this news and he threatened Holtz's daughter, which prompted Holtz to commit suicide in order to keep his daughter safe. Holtz, however, left clues about the identity of his killer, and Dash leads the way to discovering Garth's crime. Dash also realizes that Zan is not a member .of the human race, but is actually the alien who had been in contact with Dr. Holtz She is not actually present on the moon but is light years away in another galaxy. Dash and Zan agree they do not need to reveal Zan's presence to the world just yet, but Dash remains in contact with Zan.