There are 5 books in The Fallen Series.
http://www.sniegoski.com/fallen/ This series is now being published with the first two omnibus editions numbered as #1 and #2 and subsequent books numbered beginning with #3. See the series with the original numbering .
Other series related to The Fallen Series are The Fallen (Original Numbering) , Remy Chandler , Demonist and Savage .