->If I were not mad, I could have helped you. Whatever you had done, I could have pitied and protected you. But because I am mad, I hate you. Because I am mad, I have betrayed you. And because I'm mad, I'm rejoicing in my heart, without a shred of pity, without a shred of regret, watching you go with glory in my heart!
--> --'''Paula Alquist''' denouncing her husband.

Based on a 1938 play by Patrick Hamilton, ''Gaslight'' is a 1944 psychological-thriller directed by George Cukor and staring Creator/IngridBergman in her first Oscar-winning performance.

She plays Paula, a young woman who lived with her aunt, a famous opera singer. One day, the aunt is suddenly murdered and robbed by the mysterious Sergius Bauer, leaving Paula alone. After studying abroad for the ten years since the incident, she returns to England with a new husband, Gregory (Charles Boyer). But shortly afterwards, Gregory suddenly starts going out of his way to MindRape Paula.

Can Paula find out the reason for her husband's cruelty? Can a sympathetic UsefulNotes/ScotlandYard officer (Joseph Cotten) save the day?

A very-young Creator/AngelaLansbury made her film debut as the quirky maid Nancy; the performance won her an Academy Award nomination for Best Supporting Actress.

!!This movie features examples of these tropes:

* CatchPhrase: Miss Thwaites' "Well!"
* ChekhovsGun:
** One of Paula's aunt's stage gloves, given to an unnamed admirer who turns out to have been Cameron as a boy.
** The costume Alice Alquist is wearing in her portrait is where she hid the jewels.
* DomesticAbuse: One of the most iconic examples in fiction, as Gregory bullies and manipulates Paula to the point of madness.
* DrivenToMadness: Gregory pulls no punches in order to convince Paula she's going mad.
* {{Gaslighting}}: TropeMaker and TropeNamer.
* HiddenInPlainSight: How Alice hid the jewels that the tsar gave her, the ones Gregory is hunting for--on the costume she wore to the opera, amidst all the fake jewelery she wore for her performance.
* HoistByHisOwnPetard: As the page quote proudly demonstrates, Paula proudly turns Gregory's scheme to drive her to madness back on him.
* MarketBasedTitle: Averted; the play and first film adaptation were titled "Angel Street" in the U.S., but this version was released under the original title.
* ManipulativeBastard: Gregory, who sought Paula out and married her so he could get access to her house and find the jewels.
* MaybeEverAfter: At the end, Brian the detective tells Paula that he'll come by later and help her get past her trauma.
* MindRape: Gregory's mind games that he uses to convince Paula she's going insane.
* NeverMyFault: Gregory never for a moment lets Paula entertain the idea that he may be mistaken; ''she'' must be mad. At the end, Gregory insists that he and Paula could have been happy together were it not for her aunt's jewels. This is a man who has married a woman ''explicitly to drive her insane'' so she'd be committed, and murdered her aunt for the aforementioned jewels. Paula's not impressed.
* NosyNeighbor: Miss Thwaites.
* NotEvenBotheringWithTheAccent: Joseph Cotten using his own courtly Virginia accent to play a Scotland Yard detective.
* OminousFog: Lots of it around the neighborhood as Paula is led away from the house after her aunt's murder, and lots more later, when Gregory is skulking through the alleys.
* PosthumousCharacter: Alice Alquist, opera singer, lover to a tsar, owner of valuable jewels that Sergis Bauer is determined to find.
* ReallyGetsAround: Nancy the slutty maid, portrayed as explicitly as possible in 1944.
* TheRemake: This was the second film adaptation of the play; the first was a British film made in 1940. MGM ''tried to buy and burn up all the negatives'' of the 1940 version in order to avoid any competition with its film. They failed, and the earlier version survives today.
* ServileSnarker: Nancy.
* SleepingSingle: Paula and Gregory have separate rooms--of course, given Gregory's ulterior motives, this makes sense.
* TerribleTicking: One of Gregory's tricks on Paula.
* VictorianLondon