Inspector French

Mrs. X

Inspector French interrogates and investigates Mrs. X as a key suspect or witness in the case.

Mr. Duke

Inspector French works closely with Mr. Duke, likely as a colleague or informant in the investigation.

Miss Duke

Inspector French interacts with Miss Duke as part of his investigative work, possibly as a witness or person of interest.

Manley

Inspector French deals with Manley as a subordinate or assistant in the police investigation.

Mr. Gething

Inspector French consults or interrogates Mr. Gething as part of the case.

Captain Davis

Captain Davis assists or cooperates with Inspector French in the investigation.

Colonel FitzGeorge

Colonel FitzGeorge provides information or authority to Inspector French during the case.

Mr. Williams

Inspector French interviews or works with Mr. Williams as part of the inquiry.

Sergeant Carter

Sergeant Carter is a subordinate officer assisting Inspector French in police work.

Mrs. X

Inspector French interrogates and investigates Mrs. X as a key suspect or witness in the case.

Miss Duke

Inspector French interacts with Miss Duke as part of his investigative work, possibly as a witness or person of interest.

Mr. Duke

Inspector French works closely with Mr. Duke, likely as a colleague or informant in the investigation.

I: Murder!

Leads the investigation, examines the scene, and interviews Mr. Duke.

II: The Firm of Duke and Peabody

Conducts interviews and examines the crime scene, noting key evidence.

III: Gathering the Threads

Investigates the murder, forms a working hypothesis, and interviews Harrington.

IV: Missing

Investigates the disappearance of Vanderkemp and travels to Amsterdam to follow up on the lead.

French Takes a Journey

French follows the lead of the stolen notes to Reading, interviews Colonel FitzGeorge, and learns the notes may have come from the Hotel Beau-Sejour in Chamonix.

VI: The Hotel in Barcelona

Travels to Barcelona, locates Vanderkemp, and interrogates him about the murder and stolen diamonds.

VII: Concerning a Wedding

Investigates the postponed wedding and gathers information through Sergeant Nolan and his wife.

Sylvia and Harrington

Presses Harrington and Sylvia Duke with pointed questions about their movements on the night of the murder, developing and then discarding a theory involving Vanderkemp.

Mrs. Root of Pittsburg

French is rejuvenated by a new lead in the Gething case, visiting Williams & Davies and the bank to trace the diamond loan.

X: Some Pairs of Blankets

Leads the investigation, visits the Savoy and Dashford's Agency, and discovers the trunks filled with blankets.

XI: A Deal in Jewellery

French is in high spirits as he pursues the case, visiting jewellers and banks to trace Mrs. X's transactions, and later travels to Mürren to interview Mrs. Root.

XII: The Elusive Mrs. X

Leads the investigation, interviews customs officers and purser, examines passenger lists and handwriting.

Mrs. French Takes a Notion

Receives crucial insight from his wife, identifies Mrs. X as Cissie Winter, and interviews theatrical contacts.

XIV: Tragedy

Receives news of Mr. Duke's suicide, informs Miss Duke, and follows up with the solicitors and Mr. Schoofs.

XV: The House in St. John's Wood

Leads the investigation; grumbles about being on call but eagerly follows up on the identification of Mrs. Vane.

XVI: A Hot Scent

Leads the investigation, interviews bank manager and maid, and traces Mrs. Vane's movements.

A Deal in Stocks

Decodes the stock list as a cipher, deducing the escape plan.

The S.S. Enoch

Pursues the Vanes to Le Havre, discovers they have fled the ship, and later receives a telegram correcting the trail.

French Propounds a Riddle

Returns to the ship and devises a riddle competition to expose Mrs. Vane.

Conclusion

Unearths all details of the murder and theft, arranging them in proper sequence.