Hugh Drummond

Professor Goodman

Hugh Drummond relentlessly pursues Professor Goodman, who is a key figure in the criminal conspiracy, making them direct adversaries.

Mr. William Robinson

Hugh Drummond and Mr. William Robinson are on opposite sides, with Drummond trying to thwart Robinson's criminal activities.

Sir Raymond Blantyre

Hugh Drummond and Sir Raymond Blantyre are allies, with Blantyre likely assisting Drummond in his investigations.

Carl Peterson

Carl Peterson is Hugh Drummond's arch-nemesis, constantly scheming against him in a deadly game of cat and mouse.

Algy Longworth

Algy Longworth is a close friend and companion of Hugh Drummond, often assisting him in his adventures.

Ted Jerningham

Ted Jerningham is a friend and ally of Hugh Drummond, sharing in his exploits and investigations.

Mr. Edward Blackton

Hugh Drummond and Mr. Edward Blackton are adversaries, with Blackton involved in the criminal plot Drummond fights.

Professor Goodman

Hugh Drummond relentlessly pursues Professor Goodman, who is a key figure in the criminal conspiracy, making them direct adversaries.

Sir Raymond Blantyre

Hugh Drummond and Sir Raymond Blantyre are allies, with Blantyre likely assisting Drummond in his investigations.

Mr. William Robinson

Hugh Drummond and Mr. William Robinson are on opposite sides, with Drummond trying to thwart Robinson's criminal activities.

Carl Peterson

Carl Peterson is Hugh Drummond's arch-nemesis, constantly scheming against him in a deadly game of cat and mouse.

Algy Longworth

Algy Longworth is a close friend and companion of Hugh Drummond, often assisting him in his adventures.

II: In Which Professor Goodman Realises That There Are More Things in Life Than Chemistry

Discusses the diamond discovery with Algy, confronts the follower, and arranges lunch with the Professor and Toby Sinclair.

IV: In Which Mr. William Robinson Arrives at His Country Seat

Brings Brenda Goodman to the scene of the explosion, questions the Inspector, and begins to suspect foul play, deciding to investigate further.

In Which Mr. William Robinson Loses His Self-Control

Mentioned as having the notes; Robinson's adversary.

In Which Hugh Drummond Loses His Self-Control

Grieving and suspicious, he resolves to investigate Goodman's death and confronts the disguised Scheidstrun.

VII: In Which Drummond Takes a Telephone Call and Regrets It

Breaks out of a locked room, confronts Sir Raymond Blantyre about Professor Goodman's death, and reveals his suspicions about the diamond process and the Comte de Guy.

In Which Drummond Plays a Little Game of Trains

Unconscious upon arrival, then feigns madness by playing with his shoes as trains to avoid being secured and to mislead Robinson.

X: In Which Drummond Goes on Board the S.Y. Gadfly

Recovers consciousness after being knocked out, feigns unconsciousness to overhear Peterson's plans, and later feigns insanity to communicate with Professor Goodman.

In Which Drummond Leaves the S.Y. Gadfly

Frees himself from ropes, escapes the Gadfly, and rescues Professor Goodman.

XII: In Which He Samples Mr. Blackton’s Napoleon Brandy

Confronts Blackton at the Palace Hotel, having deduced his plans and followed him to Montreux. He forces Blackton to accept a duel on a glacier, burns the professor's notes, and exposes Blantyre's crimes.

In Which Drummond Receives an Addition to His Library

Morose and brooding over Peterson's escape, repeatedly saying 'Stung.' Receives a taunting letter and a mocking book from Peterson.