A soprano is murdered in London. The attacker wanted to steal her jewelry, but he runs away without the loot, alarmed by a few footsteps. The crime remains unsolved. Paula, an orphaned teenager who lives with her murdered aunt, is sent to Italy. She meets a pianist, Gregory, older than her. She falls in love with her. Wedding and honeymoon on Lake Como. Gregory wants them to settle in London, in his aunt's mansion. They barely come out. Gregory doesn't want visitors. Strange things happen to Paula. She loses items. Gregory accuses her of hiding them. He implies that he doesn't know what he's doing. He accuses her of stealing. He scolds her. He doesn't let her out of it. When she is alone, she hears footsteps in the attic and the gas lamp loses power. She explains it to Gregory, who accuses her of being paranoid.

Paula, played by the great Ingrid Bergman, has been caught in a web of confusion and lack of confidence. She doesn't know that Gregory, played by Charles Boyer, is her aunt's killer. Her plan is to get Paula admitted to the psychiatric hospital and discover the hiding place of the jewels. Luckily Brian, Scotland Yard inspector played by Joseph Cotten, will solve the web that Gregory had spun around the fragile Paula. Adaptation of Gas light, a dramatic thriller by Patrick Hamilton, this film by George Cukor gave rise to the term gaslighting, the manipulation that makes the victim, usually a woman, doubt her own lucidity. She disoriented, confused, depressed, she comes to believe she is insane.

Gaslighting is a perversion of relationships and work. But it is also a general manipulation mechanism. Parties, press and networks seem to have joined forces to confuse and mislead citizens. It is not just war, with its games of propaganda and counter-propaganda. They are the discussions around vaccines, the procés, electricity, gender, the Catalan language. Any topic, major or minor, is subjected to a constant shower of information, contradictions, rhetorical fights, anecdotes presented as categories and emotional manipulations. The overwhelming confusion leaves us abandoned in a sea of ​​doubts. Puzzled, doubting his own convictions, the citizen sinks into the swamp of disorientation.