Mr. Elmer Ludgrove

II: The Herbalist

The herbalist of Praed Street, tall and thin with white hair and beard, known for his wisdom and discretion. He listens to Mr. Copperdock's account of the Tovey murder.

III: The Inquest

Meets Mr. Copperdock for a chat about the inquest. He mentions a weekend trip to Suffolk for plant hunting but offers no new insights into the murder.

IV: The Poisoned Pipe-Stem

Returns from Suffolk with a collection of plants; listens to Copperdock's fears and advises him to go to the police.

V: Inspector Whyland

Receives Inspector Whyland, explains Copperdock's behavior as romantic interest in Mrs. Tovey, and later reassures Copperdock. Travels to Penderworth for the weekend, where he discusses the case with locals.

VI: A Middle-Aged Poet

Reads about Pargent's murder, discusses the case with Copperdock, and later speaks with Inspector Whyland, offering his theory that the murders may be the work of a maniac.

VII: The Black Sailor

Interviewed by Whyland; casts doubt on Copperdock's sighting of the black sailor; suggests a homicidal maniac may be responsible.

At No. 407, Praed Street

Listens to clients' stories and suspicions, but finds no real knowledge of the murderer; becomes convinced the criminal works alone or comes from outside the district.

IX: A Strange Affair

Provides an alibi and discusses the case with Whyland, expressing suspicion that the neighborhood is under scrutiny.

X: At Scotland Yard

Discusses the Goodwin case with Copperdock and later receives Copperdock's panicked visit after he finds counter VI.

XI: The Sixth Counter

Provides shelter to the terrified Mr. Copperdock and examines the sixth counter under a magnifying glass, noting its similarity to previous ones.

XII: A Hypodermic Needle

Discovers the body with the detective, assists Whyland in searching the house, and provides information about his own movements.

XIII: Enter Dr. Priestley

A herbalist who received a numbered counter after Copperdock's death; described as a dignified, philosophical man.

XV: The Bone Counters

Receives Hanslet and Whyland, discusses the counters calmly, later reveals to Ted and Ivy that the envelopes and typewriter match those from Ted's office.

XVIII: The Avenger

Mentioned as having received a warning counter; the Black Sailor warns him to stay out of the affair.

XIX: A Discovery

Participates in the trap by leaving London to gather herbs; returns safely.

Mr. Ludgrove's Invitation

Writes to Priestley claiming new evidence; invites him to his house; leaves Priestley alone to fetch exhibits.

XXII: The Death Chamber

Revealed to be the Black Sailor's alias; he transformed himself into the Black Sailor at Dr. Morlandson's cottage.

XXIII: The Will

Revealed to be Dr. Morlandson, the Black Sailor, who confesses to his crimes and dies in the explosion.