Sidney Young (Simon Pegg) is a small time, aspiring British journalist who works for a left-wing radical magazine. Following an incident at a party where Sidney accidentally lets a pig loose he is hired to work for an upscale magazine in New York City. He is hired by Clayton Harding (Jeff Bridges), editor of Sharps magazine, a man Sidney has previously lampooned in his own magazine.
Sidney annoys the staff he works with, first Alison Olsen (Kirsten Dunst), who is only there to pay the bills whilst she finishes her book, then his boss Lawrence Maddox (Danny Huston). He also dares to target the star clients of power publicist Eleanor Johnson (Gillian Anderson). He then meets new rising star Sophie Maes, (Megan Fox) however he is told by Lawrence to not talk to her. Sidney makes it his mission to become something within the business, however, it is almost ruined when he accidentally kills Sophie's dog. Luckily, Alison covers for him and nobody else finds out it was him.
At a party, Alison and Sidney's relationship grows when she reveals she's just ended an affair with Lawrence. Sidney stops her from driving home drunk, causing him to miss his opportuinity to sleep with Sophie. At a later party, however, just when Sidney is about to ask her out, it is revealed Lawrence has left his wife and that he and Alison are officially together. In a desperate attempt to up his career, he begs Eleanor to publish a piece on Vincent, a director he truly hates.
The next day at work Clayton reveals that both Alison and Lawrence have left, and he promotes Sidney. Sidney finally becomes successful, getting all the girls that were disgusted by him before and even catching the eye of Sophie. The night before the awards ceremony she stated that if he gives her his late mother's ring and she wins best actress, she will have sex with him. Going to the ceremony the next day he sees Lawrence, now being someone he used to be, stating that he and Alison split as she was in love with him. When the winner is revealed, he steals back his mother's ring from Sophie as she is about to collect her award, and revealing that he killed her dog. A huge fight ensues and Sidney leaves, quitting his job at Sharps and heading to New York.
He meets Alison in the park, where they are showing her favourite movie. She has finished her book and the two finally get together, with him giving her his mother's ring. The movie ends with him accidentally throwing the book onto a candle and jumping for it to stop it catching fire.