Plot
Katie Kampenfelt is an 18-year-old girl, a funny, free-spirited, lost soul who decides to take a year off before attending college. Her guidance counselor suggests she chronicle her feelings and experiences in a diary or blog.
Katie keeps her anonymous blog, called 'Undiscovered Gyrl', regularly updated with mostly sexual adventures. Initially, it's primarily with a 30+ y.o. film guy with a girlfriend, Dan, and with her teenage boyfriend, Rory. She gets a well-paid job in a bookshop with Glen, but her mother makes her quit when her partner discovers through contact with the police that he is a registered sex offender.
Although aware of Dan's impending move, he goes without saying goodbye or arranging for them to stay in contact. Her one girlfriend, Jade, calls her up after being away awhile in Greece, and they go dancing.
Katie gets a new job as a nanny for Paul, a Tufts alum who'd interviewed her for admissions, to look after his newborn. It pays well and includes a car. His wife Margaret shows her everything, and by the end of the week, she meets Paul again as he's been away for work.
Five weeks after Dan moved, Katie gets ahold of him with Jade's help. After they have full-on intercourse, he reveals he's engaged to Martine. Upset upon returning home, Katie finds Rory waiting for her with her mom and her partner Mark. He confronts her, demanding answers as he's been there for over an hour. When Katie tells Rory she's in love with the older Dan, his rage provokes Mark to throw him out.
On New Year's eve, when Katie is told her mom is engaged, she calls Rory only to find out he's now with Jade. She finally calls to meet up with Joel, a guy who tutored her in high school, for dinner. He is also taking a sabbatical, but for his mental health.
Affie, Katie's father's partner, calls in hysterics in the middle of the night, as he's had a serious fall. Going to the hospital, they are not sure if he'll recover. Sure enough, he dies. Distraught, Katie seeks out Dan and comes face-to-face with Martine, and leaves quickly as she's flustered.
When Katie shows Joel a note which Paul gave her, he thinks it is an obvious come-on. From stories she tells him about how a neighbor interacted with her when she was six, he says it's obvious she's been molested so he convinces her to see a shrink.
Within a short time, Katie has sex for the last time with Dan, the first time with 43 y.o. Paul, Joel leaves her an angry voicemail and Rory calls her a whore when she tells him she's pregnant. Her narrative begins to turn dark, particularly after the pregnancy. Joel has been hospitalized for trying to end it all. Visiting her dad's, after receiving some of his belongings from Affie, she bursts into uncontrollable sobs.
Katie tells Glenn, her former boss, some of her dark secrets. He tells her the truth about why he was in the sex offender registry. Glenn offers her a place to live and, if she chooses to keep it, to raise her baby as his own. When she gets home, she adds this to her blog, saying that moving out will be the beginning of her adult life, and the right time to stop blogging.
We learn that Katie's real name is Amy Grantham and that just minutes after that last blog post, she received a short phone call from a blocked number. She left the house in her car a few minutes later and was never seen again.
We briefly see the real versions of the people whom "Katie" had blogged about, many confirming that some –but not all –of her sexual escapades had truly happened. It is also revealed that other details had been fictionally improved in her blog, such as her best friend really being a homeless drug addict rather than the well-off "Jade" that "Katie" had blogged about, or that the baby's father, while still an older man, worked in a video store rather than being a film school professor.
The film ends with Amy’s mother, Carol Grantham, writing the truth on Amy’s blog and imploring thousands of readers for any knowledge as to where Amy might be.
