STALKER!!!
This is way too easy. Did I forget to mention that S. (not Sam) is a black belt in taekwondo and skilled in kendo?
IdentityUnknown couldn't shake off the feeling that someone was watching her. Quickly, she headed for a nearby mall, the more crowded the better. On the way she texted S., telling her that she was heading over to her house now.
IdentityUnknown ducked through the crowds and quickly hailed a taxi.