Shifters (prequel 3 of Hunted‪)‬

This book can be read first in the series with no problem. Simply read HYBRIDS next, followed by HUNTED. The two prequels then are: INVASION followed by INSURGENT.
Melissa Marn and Bruce Wilder must work under the iron fist of the SCM, while still trying to maintain humanity. Discovering a world of shifters and hybrids, the scientists must struggle with human prejudice and betrayal.