to stay with them in New York.  

Em approaches her best friend Christopher and his cousin Felix, because they are excellent computer hackers. They promise try and help Em as Nikki find her mother but only if Nikki gets them access to the Stark website. Christopher wants to take vengeance on Stark Enterprises because he blames the company for his best friend Em's death and still hasn't figured out Em has switched places with Nikki. During the investigation, Em also has to model in a lingerie fashion show, where she is accosted by another model and accused of messaging the other model's boyfriend, Justin.

At a party, Christopher finally realizes Nikki is really Em. Em also realizes there is a link between Justin's emails from Nikki and the disappearance of Nikki's mom. Using the emails, Christopher traces the whereabouts of Nikki's mom to just outside of New York City, in the home of Dr. Fong, the assistant to  neurosurgeon Dr. Holcombe who performed the brain transplant.

The group makes its way to Dr. Fong's home where they find both Nikki's mom and the actual Nikki still alive. However, Nikki's brain has been transplanted into the body of a young woman who had died while driving drunk. Dr. Fong further reveals that, upon examining Nikki's brain, he had found that Nikki had not had an aneurism as Dr. Holcombe had claimed; Nikki's brain was perfectly healthy. So, Dr. Fong had saved Nikki by transplanting her brain into another body, albeit a much homelier person's body. It's further revealed that Robert Stark, CEO of Stark Enterprises and father of Brandon, commanded Nikki to be killed, because she was trying to blackmail Robert about some business scandal.

It's also revealed that Brandon knew all, all along. The novel ends with Brandon asking Em to help him avenge his father's actions by ruining Stark Enterprises, telling her to break up with Christopher to maintain the appearance of being Nikki, and the group going into hiding from Stark Enterprises in Brandon's island home.

Airhead is the first in Meg Cabot's young adult "Airhead trilogy" and features Emerson Watts, Em for short, the 16-year-old daughter of a professor. As the daughter of an intellectual professor, Em is also a feminist and a protestor of pop-culture.

Em and her 14-year-old sister Frida couldn't be more different. Em spends time with her best friend Christopher making fun of the popular kids, pop culture, and teen idols, while Frida soaks it all up. She reads fashion magazines and drools over celebrities. So, when Stark Megastore, "featuring three stories of CDs, DVDs, video games, electronics, and books," offers a grand opening near their apartment in New York City, Frida begs to go because she knows her celebrity crush, British singer Gabriel Luna, will be there, and Em is forced to chaperon her. Supermodel Nikki Howard will also be at the grand opening because she sometimes dates Brandon Stark, heir to the Stark Megastore fortune.

Accompanied by Christopher, both Em and Frida attend the event, which is also being protested by the E.L.F., the Environmental Liberation Front, since the Stark Megastore had ousted Mama's Fruit and Vegetable Stand, which stood in the middle of the empty lot upon which the company had built the new store. At one point, protestors shoot a paintball gun at a plasma TV screen being suspended by wires from the ceiling. The wires begin to snap, and Frida, who is asking Nikki for an autograph, is standing right under the TV. Em successfully pushes her sister to safety but not in time to save herself. Th TV comes "crashing down" on Em, who goes unconscious just at the exact time that Nikki faints as well.

Em spends a month in the hospital and tries to remember what happened. When she is kidnapped by both Lulu Collins, Nikki's roommate, and Brandon Stark, Nikki's sometimes boyfriend, Em realizes that her own mind is in Nikki's body. Em traces back the events and learns that she died during the accident at the same time Nikki had a brain aneurysm. She also finds out her parents had agreed to performing the brain transplant offered by Stark Industries, in an effort to save Em. However, Em is given Nikki's body on the condition that she not break Nikki's modeling contract upon penalty of her parents facing possible criminal charges and being fined for $2 million.

Em finds herself caught up in a love triangle with Brandon Stark and Gabriel Luna but misses Christopher. She enrolls in her old school just to keep some of her old life and try to reach out to Christopher. She is also overwhelmed by the strenuous supermodel lifestyle, realizing she had misjudged it, and saddened to learn Nikki was never a true friend to Lulu. The novel ends with Em bringing Lulu home for dinner to meet her family.