Work Beneath the Investigation
The Mystery of The Invisible DogThe boys’ teamwork, salvaged equipment, and ordinary obligations establish a practical foundation for their seemingly extraordinary detective work.
increasing
Bearing strength in each event
decreasing
A Salvage Headquarters

A Salvage Headquarters
A working base
The Three Investigators meet at their hidden headquarters inside The Jones Salvage Yard. The place and its equipment reflect Jupiter Jones’s habit of turning discarded objects to use.
Independence through ingenuity
Their workshop gives the boys tools for testing ideas. Their resources come not from authority but from shared labor and practical invention.
The Secret Entrances

The Secret Entrances
A hidden route
Bob Andrews and Pete Crenshaw enter through Green Gate One and crawl through a pipe into headquarters. The route keeps their meeting place concealed.
Familiar teamwork
Their practiced movements show how naturally they share the work. The secret entrance is not a dramatic clue in the case, but it establishes the group’s cooperative habits.
An Aunt’s Complaint

An Aunt’s Complaint
Ordinary duties return
Aunt Mathilda Jones scolds Jupiter Jones for leaving without permission and assigns him appliances to sort. The detective’s life remains entangled with household and salvage-yard work.
A source of resources
The salvage yard supplies parts and income for Jupiter’s inventions. His family obligations are an inconvenience, but also part of what makes the boys’ investigations possible.
The Camera Repaired

The Camera Repaired
Salvaged technology
Jupiter Jones repairs a closed-circuit camera and monitor bought after a store fire. The equipment gives the boys a concealed view of the courtyard.
A tool adapted
The camera does not solve the case by itself, but it lets the investigators track movement and routines. Their technical advantage comes from patient reuse rather than new expense.
Records and Research

Records and Research
Bob’s contribution
Bob Andrews consults Dr Barrister and Professor Eugenia Lantine about reported wandering. His research supplies a possible framework that Jupiter can test against observed events.
Division of labor
Pete watches the suspect, Jupiter develops physical tests, and Bob researches. The case succeeds because their different strengths become complementary rather than competing.
Early morning before the first bus
The morning of the ointment experiment
The afternoon after the first investigation
The afternoon before the first courtyard watch
During the investigation at Ruxton University