Under the pen name David Shane, reporter Rowena Price (Halle Berry) and researcher Miles Haley (Giovanni Ribisi) are investigating senator Stephen Sachs, who has been having secret sexual encounters with his male interns, despite his publicly anti-gay agenda. However, the story is shut down when the source clams up (Rowena had confronted Sachs with the evidence which alarmed him and he used all his contacts to put a lid on the story and the source) and Rowena's editor, a supporter of the senator, puts a stop to the story. The editor also insists she take a vacation and will not take no for an answer.While walking home, Rowena meets her childhood friend, Grace Clayton (Nicki Aycox), who seeks her help in taking down Harrison Hill (Bruce Willis), a wealthy advertising executive. Grace gives Rowena her e-mails as proof of their extramarital affair, which Hill recently ended.A few days later, Grace is found dead, drowned and poisoned with belladonna (a highly toxic plant used to make Atrophine, used for anesthesia and to dilate the eyes and witchcraft), leading Rowena to suspect Harrison. Lieutenant Karen Tejada (Florencia Lozano) is the investigating officer. Karen interviews Grace's mother, who has Rowena sit in, as she was good friends with Grace. Grace and Rowena were together since childhood especially after Rowena's father died. Rowena finds that Grace knew about her real identity behind her pen name of David Shane, which she had guarded jealously. Rowena questions Miles, who had dated Grace in the past, and admits that he told Grace about David Shane. Cameron (Gary Dourdan) was Rowena's ex-boyfriend and turns out Grace slept with Cameron, while he was still with Rowena, tearing them apart. Rowena asks Miles to hack all of Grace's email accounts, and he finds a ton of emails to ADEX, which are sexually explicit in nature. But he can't pinpoint if ADEX is Harrison Hill. Miles is secretly in love with Rowena and spies on her as she brings Cameron home and has sex with him.Grace was revealed to be in her first trimester of pregnancy. With Miles' help, Rowena goes undercover, under the alias of Katherine Pogue, as a temporary worker at Harrison's advertising company, H2A at 7 World Trade Center.While setting up gift bags for a Victoria's Secret collection launch, she meets fellow advertiser Gina (Clea Lewis). Gina gives her information about the questionable lifestyles of the senior management of H2A. Harrison Hill is revealed to be rich because of his wife, Mia Reinhart-Hill (Paula Miranda). If she divorced him, he would be penniless, revealing the reason why he keeps his affairs with female workers secret (he paid hush money and Rowena asks Miles to sniff out the money trail). Rowena flirts with Hill both online (Miles had set up her account and added ADEX as a "friend" to it) and in real life but is warned to stay away by Hill's lesbian PA, Josie (Daniella van Graas).And Rowena is not realizing the online Hill is actually Miles, secretly in love with her. One evening Hill catches Rowena snooping, thinks she is a corporate spy, and fires her (Rowena had told her boss Esmeralda (Patti D'Arbanville) that she had temped at H2A's rival a few months. This was when Hill was looking at a leak in his office that was passing crucial account information to his rivals. Miles had given Rowena a spyware to install on Harrison's laptop as he couldn't scale the H2A firewall).Miles tells Rowena that Cameron had met Grace just 3 months ago (He had told Rowena that he hadn't seen Grace for over a yr). The kid could have been Cameron's and not Harrison's after all. Miles calls Rowena for a meeting at his home. But then Miles gets stuck at H2A where he poses as an IT technician trying to "fix" Harrison's computer. At Miles's apartment, Rowena gets in by herself & Rowena discovers a shrine to her and explicit pictures of Miles and Grace (They had had sex and Miles had photographed all of it). Miles arrives home and Rowena confronts him. He defends himself by providing evidence that Hill had access to belladonna (His wife had used Belladonna to create a whole series of photographs of close up dilated eyes) for poisoning. Rowena goes to the police, and Harrison is arrested for the murder of Grace.After Hill's conviction & sentencing in court, Miles visits Rowena. He tells her that he knows she is the real killer and has been using this investigation to frame Hill. Rowena flashes back to a memory of her father attempting to molest her, and her mother subsequently bludgeoning him to death with a fireplace poker. A younger Grace watches from her window as they bury the body. Grace has been blackmailing Rowena with this knowledge ever since.Miles describes in detail how Rowena had plotted the murder to end Grace's blackmail and pinned the murder on Hill. Miles asks how she intends to keep him quiet, implying she might sleep with him, since he has long lusted after her. However, Rowena stabs him to death and ransacks the kitchen. She then calls the police, claiming to have been attacked by Miles and that he might have been the real murderer. The film ends with a man looking out of a neighboring window, presumably having witnessed what really happened.