In conjunction with the release of Endpoint: Confluence (Book 3), the first two books in the series are free for download from the providers linked below.
For Apple/iBooks, click the following links: Endpoint: Day Zero (Book 1) and Endpoint: New Life (Book 2).
For Smashwords, click the following links: Endpoint: Day Zero (Book 1) and Endpoint: New Life (Book 2).