MySpace.com exemplifies one of the hottest Internet trends -- an online community where people post profiles in search of whatever and whoever. Think of it as a diary, but a diary you want others to read.
The social networking site allows people to design their own Web pages to reflect their personalities -- listing their likes, dislikes and hobbies.
The goal is to link up with others, forming groups with similar interests. It's as wholesome as cheerleading and baseball, or as troubling as guns, sex and drugs.
Often teens looking for new friends post profiles, not realizing that their personal information can become fair game for Internet predators. Or in Sarah's case, a disillusioned teen can hook up with a group of friends who can lead her down a very dangerous path.
"It was easier to find people who did drugs than just like walking down the street," Sarah told "Primetime." "Every weekend I would find more people, and it would get deeper and deeper."
A middle school student in the Midwest, 12-year-old Sarah was desperate to belong, trying to cope with the typical insecurities and growing pains that come with being a preteen.
"It hurt to have people hate me, to know that I didn't have any friends," she said. "On the bus one day this kid was sitting in the back all stoned, and he did not care what was going on. I wanted to be like that. I wanted to not care."
She turned to MySpace, where she found plenty of outsiders like herself. Sarah said she had started experimenting with drugs before joining MySpace but getting online created a whole new world of possibilities.
A simple search by ABC News on MySpace came up with tens of thousands of people talking about marijuana. Many more were in groups where sex was the topic, and nearly 55,000 people belonged to an online group called Drunks United.
Membership in MySpace is skyrocketing, according to the company, which claims that after 2½ years, it has more than 77 million users. MySpace has become the hot spot for music lovers and hobbyists, as well as for people looking for Mr. or Ms. Right. And more kids are signing up.
Like many parents, Sarah's mother, Janeel, was completely in the dark about what really went on online. Sarah told her mom MySpace was a place to chat with friends, and Janeel thought that seemed harmless.
"MySpace doesn't sound too threatening," Janeel said. "She said I can do and find anything on MySpace. ... And she did."
It's tough enough for parents to deal with their kids' friends they can see, but how do you deal with friends who exist only on the Internet?
"Well, it's very scary," Janeel said. "I had instincts something was wrong."
And she was right.
Thanks to her web of online friends, Sarah had a drug dealer basically in there with her -- and the 12-year-old was also lying about her age and meeting older men.
Sarah was desperate for intimacy, but the men she met were often looking for sex. She remembers one party where drugs and an older date got the better of her.
"And then I met another guy who I went to a party with, and I got really messed up ... and, um, I ended up like doing stuff with him," she said.
Even though she was in her room on her computer, Sarah was getting further and further away from her family. And sometimes she literally disappeared.