When Tom and Lily set up the Walton Detective Society, they are already immersed in a criminal investigation. The facade of famous Walton College of Rompchester University hides many ugly secrets. Theft and extortion are only the lesser of evils, because soon enough there is murder.

It all starts with the owl. During a nightly adventure, courageous Tom saves her from poachers. While taking care of the wounded bird, Tom overhears threats of don against don. And then a don goes missing. Energetic Lily insists that they investigate. They discover a map, the underground world under Rompchester and deadly secrets. Soon, they have their lists of suspects. But are they safe? Does not the murderer go to any length to cover his traces? They cannot be too careful. And soon enough, there is another murder. Cleverness and courage are now required. Just the thing for Tom and Lily.