I Know I Want a Baby, but I'm Not so Sure about a Teenager
We've done a lot of snooping in her cell phone and Explorer history (note: if you ever want to do something illicit, CLEAR YOUR HISTORY!!) and the most likely scenario is that she ditched her friend to meet up with a much older man -- a teacher from her school, no less. I don't find it weird that she hasn't called my parents, though they do. DUH! Like you're going to call Mom from your tryst with a lover! But all of us who are young enough to remember the idiocy of the late teen years are still a bit baffled that she didn't at least cover her tracks and let her friend in London know what was going on. We are still somewhat worried, but there's not much we can do.
Meditate, pray, send good vibes, do whatever you do and hope that she's just being COLOSSALLY STUPID.
UPDATE: She finally called home mid-day on Monday and is on a plane home now. She was unaware of the chaos she had generated and stunned to discover that police from four jurisdictions had been searching for her since Friday. The main thing at the moment is that she is OK and will be home in a few hours. Thanks for your concern and good wishes.