The Investigators Take the Haunting Case
The Mystery of The Invisible DogJupiter Jones, Pete Crenshaw, and Bob Andrews move from a baffling report of a haunting to a wider investigation that exposes several connected crimes.
increasing
Bearing strength in each event
decreasing
The Summons

The Summons
An unusual client
Fenton Prentice asks the Three Investigators to investigate a presence that seems to enter his locked apartment. He fears that the police will dismiss his account.
A cautious commitment
Jupiter Jones questions the story but recognizes that a real intruder may be exploiting Prentice’s fear. The boys agree to look for evidence.
The Marked Drawers

The Marked Drawers
A practical test
Jupiter Jones coats the desk handles with Investigative ointment, designed to reveal anyone who touches them. The experiment turns a supernatural-sounding problem into a physical test.
A human intruder
The smeared handles show that someone opened the desk while the boys were away. The evidence establishes that at least one visitor has ordinary, solid hands.
The Shadow Returns

The Shadow Returns
A renewed disturbance
After Mrs Bortz admits to entering Prentice’s apartment, Prentice sees another shadowy presence. Jupiter Jones recognizes a resemblance to Sonny Elmquist but cannot explain how he could enter.
The puzzle expands
The boys search for a secret passage and find none. The haunting now appears connected to a second, unexplained kind of intrusion.
Three Mysteries

Three Mysteries
A case takes shape
Back at The Three Investigators’ Headquarters, Jupiter Jones separates the shadow, the stolen sculpture, and the phantom priest into distinct questions. Their possible links give the case its structure.
A working theory
The boys suspect a local offender who knows the neighborhood and the church. Yet Sonny Elmquist’s apparent appearances while asleep prevent an easy conclusion.
The Case Closes

The Case Closes
The culprit identified
Jupiter Jones explains how John Murphy stole the Carpathian Hound, hid it in the pool, and tried to obtain ransom money. Police arrest Murphy after the failed handoff.
An imperfect resolution
The theft and the attacks are explained, but the phantom priest remains uncertain. The boys leave that last question open rather than claim a proof they do not possess.
Late afternoon during Christmas week
The morning after the first visit
The evening after Mrs Bortz is exposed
The morning after the church incident
Mid-January