Northwestern University graduate Andrea "Andy" Sachs, now living in New York with her boyfriend, aspiring chef Nate, nervously prepares for a job interview at Runway , the top American fashion magazine. When Emily, the model-thin, English first assistant to Runway 's editor, Miranda Priestly, surveys Andy's slightly frumpy appearance, she assumes that the human resources department has made a joke. Just as Emily is talking to Andy, she receives an urgent text message on her cellphone alerting her to Miranda's imminent arrival, catapulting the entire magazine staff into a panicked frenzy to arrange things precisely as the exacting Miranda wants them. While Miranda is admired as the premier American fashion editor, she also is known for her demanding, often capricious and petty requests to those around her, coupled with a lack of praise or acknowledgment of their work. Despite Miranda's complete disdain for Andy's unfashionable appearance, her interest is piqued and she decides to look at her résumé. She then dismisses Andy with her softly spoken, curt signature phrase, "that's all," but is impressed enough by Andy’s self-assured statement that she is smart and hard working that she hires her as her second assistant. Each morning thereafter, as Miranda comes into the office, she throws her coat and handbag onto Andy's desk while spewing orders, usually without adequate explanation, and refers to her as “Emily.” Although Andy's goal is to work as a journalist for a serious news magazine, she studies hard to learn about fashion and works tirelessly for a small salary, hoping that a year with Miranda will open doors for her elsewhere. Emily and others at Runway make fun of Andy's clothes and unfashionable size six figure, and her only confidante is Nigel, Miranda's pragmatic second-in-command. At first Andy resists changing her image to blend in with the others at Runway , but after Miranda reprimands her for being unable to arrange the impossible, a flight from Florida during a hurricane, Andy tearfully runs to Nigel. Rather than offer solace, Nigel tells her of the real importance of fashion and advises her to “grow up,” prompting Andy to ask for his help. The next day, after a designer makeover orchestrated by Nigel, Andy shocks Emily by arriving at the office with perfect hair and makeup and wearing designer clothes. As first assistant, Emily eagerly anticipates accompanying Miranda to Paris for autumn fashion week, during which she will be given a designer wardrobe. However, with Andy’s new image and her own observation that Miranda is starting to rely more on Andy, she becomes increasingly stressed. Some time later, Miranda obliquely acknowledges Andy’s value by calling her Andrea for the first time and asks her to deliver "the book" to her home that night. Later, at the office, Emily tells Andy that the book, the daily mock-up of the magazine's layout, must be delivered, along with Miranda's dry cleaning, to her townhouse. Although Emily sternly warns that the instructions must be followed silently and to the letter, once inside Miranda’s house that night, Andy is confused about where to put the dry cleaning. Miranda's young twin daughters, Caroline and Cassidy, help her out, then puckishly tell her to bring the book upstairs. As Andy climbs the stairs, she is embarrassed to hear Miranda's husband Stephen lashing out at her, drops the book and backs down the stairs as Miranda turns and glares at her. As the months go by, Andy's long hours of work and erratic schedule causes problems in her relationship with Nate and her closest friend, art gallery manager Lily, who feel that Andy is changing. One day, Miranda tells Andy that her daughters need to have a copy of the next Harry Potter book, which has not yet been published, in time to take a train trip to see their grandmother that afternoon. Panicked at the impossible task, and knowing that a failure will cost her her job, Andy calls well-connected writer Christian Thompson, whom she met and flirted with at a party for trendy designer James Holt. With Christian’s help, Andy is able to obtain the manuscript, startling the almost speechless Miranda. Some time later, on the evening of a large reception that Emily is scheduled to attend with Miranda, Andy is about to leave the office early for Nate's birthday party when Miranda says that she wants both assistants to accompany her. With three notebooks of faces and names to memorize to prompt Miranda at the reception line, Andy calls to assure the skeptical Lily that she will be a bit late. Arriving at the reception in a Valentino gown that impresses Emily as well as Nigel, Andy outshines Emily by whispering the name of an approaching ambassador into Miranda's ear when Emily cannot recall his name. Despite Andy’s success, missing Nate’s party widens the rift between them. Just before the trip to Paris for fashion week, Miranda, who increasingly relies on Andy as her first assistant, tells her that she needs the best team with her to Paris and that no longer includes Emily. Andy protests, but Miranda lets Andy known that her own future depends on taking Emily's place. The next morning, when Andy tells Miranda that she has accepted the offer, Miranda throws her coat and bag on Emily’s desk, then quietly tells her to call Emily and "tell her now." However, as the jaywalking, overwrought Emily answers her cellphone, she is hit by a taxi and seriously breaks her leg. At the hospital, Andy tells her about the Paris trip and tries to downplay her own complicity, but Emily orders her to leave. At an opening reception in Lily’s gallery that night, Andy again meets Christian, who asks if she will be going to Paris and suggests that they have dinner there. She declines because of Nate, but when Christian kisses her on the cheek, Lily is watching and misinterprets, then lashes out at her for changing. When Nate overhears them talking about Andy’s trip to Paris, he leaves the gallery. Outside he accuses Andy of starting to become like Miranda and they argue, after which she says that the trip is probably good because they need a break. In Paris, Andy is awed by the glamour of fashion week, and when Christian asks her to join him for dinner that night, she agrees. Andy then goes to Miranda’s suite and is shocked to find her in a robe, with no makeup and uncombed hair. Miranda wants to go over the seating charts for the following day's reception for James and reveals that her husband is divorcing her. She also talks about the damage the gossip will do to her little girls, but ignores Andy’s expression of sympathy. Later, Andy is visited by Nigel, who applauds her newly acquired sense of style and opens a bottle of champagne to celebrate the fact that he is going to be James’s business partner in a venture that will be announced at lunch the following day. He relishes the fact that all of his years of hard work will finally reap rewards and says that Miranda has gotten him the job. Later, at dinner with Christian, he tells her that she is far too nice to be with Miranda, and after sightseeing on the left bank of Paris, the couple start to kiss and go back to his hotel. The next morning, when Andy oversleeps, her haste to get dressed causes her to knock over some things in Christian’s room and uncover a mockup of a new Runway cover. When she confronts him, he reveals that it is a sample of what the magazine will look like when Jacqueline Follet, Miranda’s rival and counterpart at the French edition of Runway , is the new American editor. He also says that he will be in charge of editorial and that Irv Ravitz, who heads Elias-Clarke, the publisher of Runway , will tell Miranda after lunch. Andy angrily leaves him and tries to speak with Miranda, but Miranda will not listen to her until they are walking into the lunch for James. After hearing Andy’s story, Miranda acts as if she has said nothing of interest, and when Miranda comes to the podium to announce James's new business, she tells the audience that Jacqueline will be his partner. Though shattered, Nigel maintains his composure and wistfully tells Andy that Miranda will repay him someday, when the time is right. Riding in their limo after lunch, Miranda informs Andy that she knew all along about the attempt to push her out of Runway but had been negotiating with powerful designers who had threatened to withdraw all advertising from Runway if she left. She also reveals that she had confronted Irv and arranged for Jacqueline to become James's partner. Grateful for Andy’s loyalty, though, she tells Andy that she reminds her of herself. Andy retorts that she could not have hurt a friend as she hurt Nigel, but Miranda assures her that she already has: Emily. Realizing that Miranda is right, as the limo stops, Andy says that she does not want this kind of life, but Miranda asserts that everyone does. As Miranda approaches a crowd of reporters, Andy walks away and throws her cellphone into a fountain. Some time later, wearing her own clothes, Andy meets Nate at Starbucks to tell him she has quit and is interviewing for another job. Nate reveals that he has taken a sous chef position in Boston, but the two agree that they will work something out. At her interview, Andy is told by the editor that when he asked for a recommendation from Runway , he received a fax from Miranda stating that Andy was her greatest disappointment but he would be crazy not to hire her. Later, Andy calls Emily and offers to give her the clothes from the Paris trip, prompting Emily to tell Andy’s replacement that she has some big shoes to fill. Moments later, Andy sees Miranda getting into her limo and Andy waves. Unknown to Andy, as she walks away, Miranda smiles warmly for a brief moment, then barks at her driver "Go!"