A while ago I read a book and it was in a series and I just can't quite remember the name of the book, the series, or even the author. In the book, there is this girl who drives a Harley Motorcycle and her nickname is Harley. One day, her father goes missing and she wants answers as to why. In this book there is also this guy she ends up getting help from. He claimed to be abducted by aliens who preformed tests on him. There questions lead this to this old military base where Harley's father was preforming work. They tell her that her father is just on a "business trip" and will be back.
There was a mysterious guy that found them and helped them by giving them clues. He also gave Harley a chance to start over since the "bad guys" knew her and would look for her.

I know it was older and they were about 150-250 pages.