Emma Pass 
The Fearless 

The Fearless. An army, powered by an incredible new serum that makes each soldier stronger, sharper, faster than their enemies. Intended as a force for good, the serum has a terrible side-effect – anyone who takes it is stripped of all humanity, empathy, love. And as the Fearless sweep through the country, forcing the serum on anyone in their path, society becomes a living nightmare.
Cass remembers the night they passed through her village. Her father was Altered. Her mother died soon after. All Cass has left is her little brother – and when Jory is snatched by the Fearless and taken to their hellish lair, Cass must risk everything to get him back.