Put the book back in the fantasy section of the library where it came from.
But if you're still worried, install Avast or Lookout to be sure.
Getting your gmail password (maybe by offering to check whether you got the email you were waiting for) is a much easier way to track where your cellphone is. If you may have ever done that, go change it on gmail, delete the account from your phone and create a new gmail account on the phone with the new password. (Go to Android Device Manager - locate your phone
and you'll see why you should never give anyone your password unless you don't mind their tracking you. You may have to move the box to see the part of the map - and the indication of your location - you're located in.)