A motorcycle police officer notices a luxurious car parked on a road with its female driver just sitting there. He asks the woman if anything is wrong, she is unresponsive, then seems dazed for a moment, says no, then drives off at very high speed. The car crashes and ends up in the front yard of a house. The owner of the house is a doctor, who, with the officers help, brings the woman into the house and puts her on a couch, where she says she wants no help.
Dr. Richard Caleb (Morris Carnovsky) is a psychiatrist and guesses she was trying to kill herself. He tells her he knows how to help suicidal people and she takes his card as he puts her on a commuter train to go back to town.
The next morning we see the woman (Hedy Lamarr) arriving late for work at a fashion magazine, and she overhears some men saying to each other that Madeleine is the problem. We learn that her name is Madeleine Damian, that she is the art editor, having much responsibility and a fancy executive office at the magazine. She confronts the group of men and threatens to quit if the magazine doesnt go along with her artistic decisions about the advertising for an important client, Felix Courtland (John Loder), a diamond dealer.
In conversations among the people at the office it becomes clear that she has had lots of relationships with men at work, and others, that she is good in her profession, that she uses her beauty and style to attract men, whom she discards easily when they have served her purpose. Madeleine overhears her secretary make gossipy comments about why she might be late, and the girl is fired on the spot.
Jack Garet (William Lundigan), one of Madeleines coworkers who evidently is an ex, attempts to intercede in favor of the secretary, but he is brushed off. Jack is also brushed off with a smile but with disdain when he tells her he needs money and wants to borrow 500 dollars from her.
Later she encounters diamond dealer Courtland for the first time, smiling while she tells him she wont bend on the matter of rejecting his advertising art. Courtland is smitten by her, uses the fact that cabs are hard to get in pouring rain to insist on giving her a ride in his limousine, and pours on the charm while displaying his great wealth in front of her at his luxurious mansion, making sure she sees he has a concealed safe in his library workroom. A large painting in the room is a work by Madeleines father, which triggers conversation where we learn of Madeleines childhood and artistic talents.
Weary of the game of selling herself and fending off wolves, Madeleine looks up Dr. Caleb and after an initial interview decides to put herself in his psychiatric care, trying to redo her interior life and learn how to be a happier by giving up pretenses and become a genuine person.
Under his orders, she quits her job and moves into a small flat under a new identity, starts painting and living the life of an artist, and has no contacts with anyone from the magazine.
Her landlady (Margaret Hamilton) tells her downstairs neighbor, Dr. David S. Cousins (Dennis OKeefe) that she is an artist, and it just turns out that he needs illustration art to publish medical research he is doing. So she meets handsome young bachelor David, she begins to interact with him in his apartment, peering into microscopes and making drawings of what she sees. He is direct and uncomplicated and has no secrets or guile, no pretenses, so different from the men of her previous world that she falls in love with him. After a short time when he has his mind only on his research project, he notices how beautiful she is, and he gets smitten also.
Now things immediately get very complicated for Madeleine. Felix finds out where she lives, enters her apartment and waits for her, where he pressures her to return to her old life.
When his research project is finished, and a paper on the results is about to be published, they celebrate. He needs to find a job, they talk about him going to Oregon to set up a practice, and he proposes marriage. She doesnt give him an outright yes because she fears what might happen if he found out that she had assumed a false identity to conceal her past relationships. Just then his boss sends him to a conference in Chicago for a few days, and she knows that she must make tough decisions before he returns.
She consults Dr. Caleb, who says she can have no future with David if she continues to keep secrets from him.
Madeleine and David, at the airport, happen to meet Jack Garet and Felix Courtland, and she realizes that she will have to give David some account of her past. She makes contact with Ethel Royce (Natalie Schafer), her best female friend from her old job, meets her at a restaurant to catch up on events, where she is seen by her old boss and Jack. Jack calls Felix, and he comes immediately to the restaurant to renew contacts.
Then come the fateful sequence of events. Jack had become a confidant and secretary to Felix. Needing money, Jack had removed a valuable diamond from the safe at Felixs house, and pawned it. Felix became aware of the theft and knew that only Jack could have removed the diamond, threatening Jack.
Jack arrives at Felixs house to beg for time while Madeleine is there, in Felixs fancy room, where she had been brought in to recover from drinking too much with Ethel. Madeleine wakes, hears the voices, escapes by going out towards the rear. Jack and Felix enter the room, continue arguing, Felix takes the phone to call the police, and Jack clobbers him over the head with a heavy table lighter.
When the detectives investigate, the evidence points to Madeleine as the killer. She had been seen arriving there by servants and chauffeurs, her fingerprints were on the cigarette lighter, Felix had been seen by the landlady at Madeleines apartment, her double identity is very suspicious, the fact that she had received a proposal of marriage from David, and that he was unaware of her past, gives a motive.
When David learns of her deceptions and her past, he becomes very disillusioned and believes she is the killer.
Dr. Caleb sees that she is suicidal again, committing suicide by murder trial, refusing to cooperate with her defense attorney, although she may well be innocent. He approaches David and by his persistence gets David to admit he is still in love with her and would love her even if he had known about her past, and explains to him that to her, he is her judge and jury, and wants to die because she thinks their love has no chance.
After David answers, under oath, that he is still in love with Madeleine, she regains hope, she agrees to testify, and testifies that she heard an altercation of Felix with another man, plus the detail that Felix had a concealed safe in his room, where he kept diamonds. The lawyer and court agree to suspend the trial until the existence of the safe is verified. David is present when the safe is discovered by police, and after the police leave, comments that there might be fingerprints on the dials if in fact there was someone who entered the room to rob the safe. He also noticed that Jack knew that the safe was opened by a key and not by the customary combination.
David pretends to leave, but he returns, to see Jack carefully wiping the dials on the safe. David figures out that Jack is the killer, there are scuffles, reaches for guns, but the murder details have been solved enough to convince the court that Madeleine is not guilty.
The newspaper headlines scream that Madeleine is freed, Madeleine and David make up and all the good guys can try to live happily ever after.