Grace Walden and her friends are all on the school swim team. This year, they have a new coach, Coach Sheila. Coach Sheila wants to push the girls and win a championship. She decides the team needs more practice and motivation and convinces the swim team parents to allow her to take the girls to a nearby lake for a swim camp lasting several days. Grace, the twins Silver and Gold, and Lisa Acre are best friends and consider each other as sisters. Grace and her friends are excited about attending camp together and look forward to having some downtime to explore their surroundings. Besides making a new friend—the good-hearted prankster Zeke—the kids also find a mysterious cave and meet interesting and bizarre locals. What these kids do not know is that Coach Sheila has secrets of her own.
Walraven's book is geared toward middle-grade readers as the mystery, danger, and themes are not suited for younger readers. There is a lot of trouble surrounding the protagonist and her friends, and they are subjected to a level of violence that necessitates a more mature audience for the book. Also, one of Grace's friends deals with parental neglect. In addition, the novel deals with physical abuse being passed down from parents to children and the issues that can arrive from the abuse of power—in this case, in the form of Coach Sheila. The book also deals with violence in schools and during school functions, something that, in light of the many school shootings in recent times, readers and their parents should be aware of before picking up this book. These elements provide tension and move the plot along at a quick pace. The illegal gamblers in the cave and the girls' violent, schizophrenic coach present a real threat to the main characters. Walraven does a good job including interesting characters, especially the woodswoman Izzy with her bizarre menagerie of animals that she keeps and calls her babies. These unique side characters offer a break from the tension and are used in interesting ways as the plot unwinds.
The story unfolds a bit like a Scooby-Doo episode, but with more realistic threats to the young explorers. Although they voice slight reservations, the book's antagonists are all looking to get ahead and are not above hurting children to get what they want. Reading Walraven's book, comparisons to Mark Twain's The Adventures of Tom Sawyer come to mind. The protagonists in both stories discover interesting people and places while exploring, and these discoveries lead them into danger. Some additional editing would enhance the effectiveness of the book's narrative. However, readers who get past this will find a tale full of adventure and harrowing danger. The young swimmers are quite worried about what the illegal gamblers are planning to do to them, and they realize too late that it is their own coach who may be the bigger danger. Middle-grade readers who like exciting plots with peril and exploration, and do not shy away from slightly more mature content, may find this to be a thrilling read.