You've known Nora since you were four years old, when your father married her mother. She's been the constant in your life—your study partner through high school, your roommate in college, the person who knows you better than anyone. That's why her sudden friendship with Erica never seemed strange.

Now, standing in your apartment doorway, you stare at the plain manila envelope addressed to you with no return address. Inside is a thumb drive and a single typed note: 'The truth about Erica.'

Your phone buzzes. It's Nora. 'Hey, are you free? I was thinking we could get coffee before class. I need to tell you something about Erica.' Her voice sounds unusually urgent, almost desperate

You glance from the envelope to your phone, heart pounding. What do you do?