Norman Gale

"- Poirot: You left your fingerprints on the bottle. - Gale: You lie! I wore — (trailing off, realising what he just said) - Poirot: Ah, you wore gloves? I think, monsieur, that little admission cooks your gander."

- Gale was trapped by Poirot into slipping the details of murder

Norman Gale is the main antagonist of Dame Agatha Christie's 1935 Hercule Poirot novel, Death in the Clouds. He is an American dentist and the initial love interest of Jane Grey, but in secret, he married Anne Morisot and decided to kill off her mother, Madame Giselle, in order to inherit her fortune, before killing off Anne and be together with Jane, whom he was genuiuely in love with.

He is portrayed by Shaun Scott in Agatha Christie's Poirot.

History
Norman Gale was initially introduced as a supporting figure during Poirot's investigation on the death of Madame Giselle, who was killed by a poisonous dart on the plane. In the climax, however, Poirot revealed in his dénouement that Gale was the true killer.

It was revealed that Gale already met Anne Morisot in Canada and discovered she was the daughter of Madame Giselle, a wealthy moneylender, and decided to marry her and inherite her mother's fortune through murder. Willing to become Gale's accomplise, Anne showed no compassion to her mother, who had gave her up and sent her to Canada in twenty years ago.

Prior to the murder, Gale set up the plot to manipulate Madame Giselle into taking the flight he would take through bribing the airport. He bought a blowpipe from Paris and prepared a poisonous dart. Before the flight, he brought his dentist uniform onboard and dressed it while using lavatory. The dentist uniform bore a striking similarity to an air steward's uniform, and no one would pay attention to a steward. As a result, Gale managed to kill Madame Giselle by stabbing her with the dart directly, after pretending to present her a tea spoon. He later prepared a dead wasp and pretended that Madame Giselle died of wasp stings.

Originally, Gale tried to frame Lady Horbury by putting the unused blowpipe beside her seat. However, Lady Horbury switched her seat with Poirot in order to avoid sitting near Madame Giselle. As a result, the murder was pinned on Poirot instead. Anne Moisort was also on the flight as Lady Horbury's maid, but her presence was unexpected to Norman. Later, after Anne claimed her inheritence on the same day Poirot found her, Gale killed Anne off.

Poirot managed to deduce the murderer's real method through making a small experiment on another flight, which revealed that no matter how he tried, he could never blow a dart to anyone without being noticed by other passengers. As a result, he deduced that both the dead wasp and the blowpipe were distractions. Gale originally denied Poirot's accusation during his dénouement, but Poirot managed to trap Gale that he discovered Gale's fingerprints on the bottle of poison. Gale inadvertently slipped the truth that he wore gloves, and tried to attack Poirot when finally cornered. Nevertheless, he was subdued by the police and was then arrested.

Trivia

 * In Agatha Christie's Poirot, Norman didn't attack Poirot when he was cornered, and he quietly accept his arrest.