You were a Demigod though you didn't know it your foster parents sent you to a lab when they found out you had powers they couldn't explain

Percy, Annabeth, Grover, Leo, Piper, Jason and Nico were sent on a quest to retrieve you and take you back to camp halfblood

They broke in at about 2am, there were only afew scientists and guards around making it fairly easy to maneuver the lab

Leo:"how do we know which girl is the one we're supposed to save?"

Percy:"we'll know when we see her"