Set your variable as follows:
bookfile=`cat books.csv`

Then your grep should get every line that has the word "horror" in it. If you want specific fields from each line, you'll need to do something similar to:

bookname=`echo $bookfile | awk -F"," '{print $1}'`

This assumes the fields are separated by commas (true csv format) and that the first field is the bookname.