# Derek Kettering — The Mystery of the Blue Train character guide > Derek Kettering in The Mystery of the Blue Train by Agatha Christie. **Role:** major **Also known as:** Mr. Kettering, Derek, M. Kettering, Monsieur Kettering **First appearance:** 0005-iv-in-curzon-street ## Snapshot A charming, debt-ridden husband whose careless wit and convenient alibi make him the most obvious and least comfortable suspect. ## Who they are Derek Kettering moves through the story with the easy manners of a man who has never had to earn anything, and the mounting debts of one who has spent everything anyway. He is travelling on the same train as the wife he is about to lose, accompanied by the dancer Mirelle, and his flippant remark that dying on a train causes 'all sorts of legal and international complications' lands with grim irony. Van Aldin despises him; the police watch him; and his genuine shock at the news sits uneasily beside the two million pounds he stands to gain. ## Relationships ### [Katherine Grey](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/katherine_grey) _romantic_ Derek is drawn to Katherine's calm and genuine nature, developing romantic interest after his wife's death. ### [Hercule Poirot](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/hercule_poirot) _rivalry_ Derek is initially hostile and suspicious of Poirot's investigation, fearing he will be accused. ### [Ruth Kettering](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/ruth_kettering) _family_ Derek and Ruth are estranged married couple, with deep resentment and financial conflicts. ### [Comte de la Roche](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/comte_de_la_roche) _rivalry_ The Comte and Derek are bitter rivals over Ruth and her fortune, each suspecting the other of murder. ### [Hercule Poirot](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/hercule_poirot) _rivalry_ Derek is initially hostile and suspicious of Poirot's investigation, fearing he will be accused. ### [Ruth Kettering](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/ruth_kettering) _family_ Derek and Ruth are estranged married couple, with deep resentment and financial conflicts. ### [Hercule Poirot](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/hercule_poirot) _rivalry_ Derek is initially hostile and suspicious of Poirot's investigation, fearing he will be accused. ### [Katherine Grey](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/katherine_grey) _romantic_ Derek is drawn to Katherine's calm and genuine nature, developing romantic interest after his wife's death. ### [Katherine Grey](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/katherine_grey) _romantic_ Derek is drawn to Katherine's calm and genuine nature, developing romantic interest after his wife's death. ### [Comte de la Roche](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/comte_de_la_roche) _rivalry_ The Comte and Derek are bitter rivals over Ruth and her fortune, each suspecting the other of murder. ### [Ruth Kettering](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/ruth_kettering) _family_ Derek and Ruth are estranged married couple, with deep resentment and financial conflicts. ### [Comte de la Roche](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/comte_de_la_roche) _rivalry_ The Comte and Derek are bitter rivals over Ruth and her fortune, each suspecting the other of murder. ## In the story ### [The Mystery of the Blue Train](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/the-mystery-of-the-blue-train) Ruth's estranged husband, whose presence on the train raises suspicion and conflict. ### [In Curzon Street](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/iv-in-curzon-street) Mentioned as Ruth's unfaithful husband who is seeing Mirelle; Van Aldin plans to meet him the next morning. ### [A Useful Gentleman](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/v-a-useful-gentleman) Visits Van Aldin; argues against the divorce, hints at Ruth's own secrets, and warns Van Aldin to seek frankness between father and daughter. ### [VI: Mirelle](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/vi-mirelle) Visits Mirelle after a tense interview with Van Aldin; defends his wife's honor against Mirelle's insinuations. ### [An Offer Refused](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/ix-an-offer-refused) Derek books a Blue Train ticket under the name Pavett, contemplates his financial troubles, and refuses Van Aldin's bribe of one hundred thousand pounds. ### [At the Villa Marguerite](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xii-at-the-villa-marguerite) Derek arrives for dinner at the villa, unaware of his wife's murder. He recognizes Katherine from previous encounters and is later summoned by the Prefect of Police, showing his ignorance of the crime. ### [Van Aldin Gets a Telegram](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xiii-van-aldin-gets-a-telegram) Reported by Mr. Goby to have left London for the Riviera on the Blue Train the previous morning. ### [XVI: Poirot Discusses the Case](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xvi-poirot-discusses-the-case) Discussed as the husband who refused a divorce bribe, traveled with Mirelle, and inherits two million pounds from Ruth's death. ### [An Aristocratic Gentleman](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xvii-an-aristocratic-gentleman) Questioned by the magistrate and Poirot; denies seeing his wife on the train and reveals knowledge of the rubies. ### [XVIII: Derek Lunches](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xviii-derek-lunches) Derek is moody and drinks cocktails before being approached by Mirelle. He rejects her and invites Katherine Grey to lunch. ### [An Unexpected Visitor](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xix-an-unexpected-visitor) Mirelle accuses Derek Kettering of murdering his wife, claiming he boasted of it beforehand and traveled on the same train to kill her. ### [Katherine Makes a Friend](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xx-katherine-makes-a-friend) Discussed by Katherine and Lenox; Katherine recalls his remarks about his wife's death and his attractiveness. ### [At the Tennis](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxi-at-the-tennis) Appears reckless and angry; questioned by Poirot about the cigarette case. ### [A New Theory](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxiii-a-new-theory) Implied as a possible suspect; Poirot suggests he may have been the man talking to Ruth at the Gare de Lyon. ### [XXIV: Poirot Gives Advice](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxiv-poirot-gives-advice) Seen speaking earnestly with Katherine Grey; later confronts Poirot about his feelings for Katherine and his break with Mirelle. ### [XXV: Defiance](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxv-defiance) Confronts the Comte de la Roche and later Mirelle, refusing blackmail and asserting his innocence. ### [A Warning](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxvi-a-warning) Derek confesses to Katherine that he entered his wife's compartment on the train, but denies murdering her, and declares his love for her. ### [Interview with Mirelle](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxvii-interview-with-mirelle) Accused by Mirelle of murdering his wife; she claims to have seen him leave Ruth's compartment before the train reached Lyons. ### [XXVIII: Poirot Plays the Squirrel](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxviii-poirot-plays-the-squirrel) Arrested for the murder of his wife; Lenox is informed of this by Poirot. ### [XXXI: Mr. Aarons Lunches](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxxi-mr-aarons-lunches) Mentioned as being in prison, suspected of murdering his wife on Mirelle's account. ### [XXXII: Katherine and Poirot Compare Notes](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxxii-katherine-and-poirot-compare-notes) Mentioned as the prime suspect; Poirot questions whether he would have disfigured the victim's face. ### [By the Sea](https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/chapters/xxxvi-by-the-sea) Released from custody and has left Nice for St. Mary Mead. ## Links - HTML: https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters/derek_kettering - Book: https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se - All characters: https://www.betterreads.dev/discover/the_mystery_of_the_blue_train_se/characters