World-famous opera singer Alice Alquist has just been murdered. The perpetrator bolted, without the jewels he sought, after being interrupted by a childâPaula (Terry Moore)âAlice's niece, who was raised by her aunt following Paula's own mother's death years earlier.Paula is sent to Italy so that she can train to be an opera star with the same teacher who once trained Alice. Paula studies with him for years, all the while trying to forget that terrible night at Number 9 Thornton Square in London, England.Now an adult, Paula (Ingrid Bergman) meets Gregory Anton (Charles Boyer), and soon falls in love with him. Paula eventually ends her long tutelage to marry him. Gregory persuades her that they should live in the long-vacant London townhouse her aunt bequeathed her and, to help calm her anxieties, suggests they store all of Alice's furnishings in the attic. Before they do, Paula discovers a letter addressed to her aunt by a man named Sergius Bauer, dated only two days before the murder, tucked away in a music book. Gregory's reaction is swift and violent; however, he quickly composes himself, explaining his outburst as one of frustration at the bad memories his bride is experiencing.After Alice's belongings are packed away in the attic and the door blocked, events take a turn for the bizarre. At the Tower of London, Paula loses a brooch that Gregory had given her, despite its having been stored safely in her handbag. A picture disappears from the walls of the house, and Gregory says that Paula took it, but Paula has no recollection of having done so. Paula also hears footsteps coming from above her in the sealed attic, and sees the gaslights dim and brighten for no apparent reason. Gregory suggests that these are all figments of Paula's imagination.Charles Boyer and Ingrid Bergman in Gaslight. She has discovered a letter.Gregory does everything in his power to isolate his wife from other people. Gregory allows her neither to go out nor to have visitors, implying that he is doing so for her own good, because her nerves have been acting up, causing her to become a kleptomaniac, and to imagine things that are not real. On the one occasion when Gregory does take her out to a musical gathering at a friend's house, he shows Paula his watch chain, from which his watch has mysteriously disappeared. When Gregory finds it in her handbag, Paula becomes hysterical, and he takes her home. Paula begins to believe she should not go out in public.The young maid, Nancy (Angela Lansbury), does little to improve the situation. Whenever she shows up, her face betrays a feeling of disdain; Paula becomes convinced that Nancy loathes her.Unknown to Paula, her husband is in fact Sergius Bauer, her aunt's murderer. He sought out Paula in Italy, managed to win her heart, married her, and suggested they live in London, all with the aim of getting back into the house to continue searching for Alice's jewels. He has been secretly rummaging through Alice's belongings in the attic to find the jewels he is certain are there. The footsteps Paula hears in the attic are thus his, and the flickering gaslights he claims she has imagined are in reality caused by him turning the attic lights on, reducing the flow of gas to the downstairs lights.Gregory does everything in his power to convince his wife that she is going mad. If she were certified insane and institutionalized, he could search without impediment for the jewels. The plan almost works. Paula is saved by her trip to the Tower of Londonâalthough this visit was the catalyst that enabled Gregory to cement his control over her, it also led to a chance encounter with Inspector Brian Cameron of Scotland Yard (Joseph Cotten), an admirer of Alice Alquist since his childhood. Seeing Paula, whose resemblance to her aunt catches his attention, rekindles Cameron's interest in the cold case, an interest that is heightened when he learns that Alquist was in possession of valuable jewels that were never found. Cameron was also present at the aforementioned musical gathering, and thus witnessed Gregory's strange behavior from an independent perspective. With the aid of the police constable on the beat, Cameron figures out that Gregory slips into a vacant house on the same street, goes on to the roof, and enters his own attic via a skylight. Cameron eventually manages to get inside the house and see Paula while Gregory is in the attic. Her sanity is quickly restored when he confirms that the gaslights are indeed flickering and she discovers the letter from Bauer that Gregory had told her was a figment of her imagination. On that same evening, Gregory at last discovers the jewels he has sought for so long: hidden in plain sight, disguised as costume jewelry. However, when he comes down, Cameron accosts him and with the help of the constable arrests him and ties him up.Paula indulges herself in a bit of revenge as she psychologically tortures Gregory after he has been bound to a chair, tantalizing him with the suggestion that she might free him so he can escape arrest, trial, and execution, before calling in Cameron to take him away.
Output: Question: What is the name of the detective?, Answer: Brian Cameron