Mark Ablett

Bill Beverley

Bill is a loyal friend to Mark, though he becomes troubled by Mark's possible guilt.

Antony Gillingham

Antony is fascinated by Mark's behavior and suspects him of being a manipulator or murderer.

Matthew Cayley

Matthew is Mark's secretary and business manager, but their relationship is strained by distrust.

Robert Ablett

Mark and Robert are brothers, with a history of bitter rivalry and animosity.

Miss Norris

Miss Norris is Mark's housekeeper, and their interactions are formal and businesslike.

Inspector Birch

Inspector Birch interrogates Mark as a primary suspect in the murder investigation.

Mrs. Stevens

Mrs. Stevens works as Mark's cook, and their relationship is strictly employer-employee.

Bill Beverley

Bill is a loyal friend to Mark, though he becomes troubled by Mark's possible guilt.

Antony Gillingham

Antony is fascinated by Mark's behavior and suspects him of being a manipulator or murderer.

Inspector Birch

Inspector Birch interrogates Mark as a primary suspect in the murder investigation.

Matthew Cayley

Matthew is Mark's secretary and business manager, but their relationship is strained by distrust.

Robert Ablett

Mark and Robert are brothers, with a history of bitter rivalry and animosity.

The Red House Mystery

Owner of the Red House, whose brother Robert is the murder victim.

I: Mrs. Stevens Is Frightened

The master of the Red House, who announced his brother's visit at breakfast and is not found in the office or Temple.

Mr. Gillingham Gets Out at the Wrong Station

Host at the Red House; receives a letter announcing his brother Robert's impending visit, which visibly upsets him.

III: Two Men and a Body

Mentioned as the brother of the victim and cousin of Cayley; absent from the scene; implied to have been the last person with Robert before the shot.

IV: The Brother from Australia

Mentioned as having received the letter from Robert, coming downstairs, entering the office, and being absent after the shot; his whereabouts and actions are central to the inquiry.

Mr. Gillingham Chooses a New Profession

Missing and presumed by the Inspector to have shot his brother Robert.

VII: Portrait of a Gentleman

Described as vain, self-important, and a meticulous host who arranges his guests' activities, leaving them feeling constrained.

VIII: “Do You Follow Me, Watson?”

Mark is discussed as the possible shooter, but Antony questions whether he would commit such a foolish murder.

X: Mr. Gillingham Talks Nonsense

Discussed as possibly having drowned himself or escaped via the secret passage; Antony theorizes he discovered the passage a year ago.

XI: The Reverend Theodore Ussher

Referenced as the one who rearranged the library and discovered the secret passage a year ago; his potential hiding place is the focus of the chapter.

XII: A Shadow on the Wall

Suspected of catching the 4:20 train to London; described as well-to-do and volatile.

XIII: The Open Window

Discussed as the shooter of Robert and as having a distinctive high-pitched voice. Antony theorizes that Mark consulted Cayley after the shooting and then hid in the secret passage.

XV: Mrs. Norbury Confides in Dear Mr. Gillingham

Discussed by Mrs. Norbury as the intended husband for Angela; his whereabouts remain unknown.

XVI: Getting Ready for the Night

Believed by Antony to be dead, his body hidden in the secret passage.

Mr. Beverley Takes the Water

Discussed as possibly having escaped with Cayley's help or having been killed by Cayley.

XVIII: Guesswork

Subject of suspicion; Antony argues he knew about Robert's visit earlier than claimed.

Mr. Beverley Is Tactful

Discussed in Antony's questions; known to love acting, visit dentist Cartwright, and hate swimming.

XXI: Cayley's Apology

Described as vain, artistic, and a heavy drinker; Cayley manipulated him into impersonating Robert before killing him.

XXII: Mr. Beverley Moves On

Revealed to have disguised himself as Robert; his finicky habits and acting background are discussed.