This is Book 2 of the Bloodlands.

After the vampire named Gabriel came into her life, Mariah was forced to face her nature and admit to  doing things that Gabriel could not forgive.

To redeem herself and recover her humanity, she sets out in pursuit of a rumored cure and Gabriel, blood-bonded must follow. Together, yet apart, they will face danger and death as well as the hoped-for cure leads them into dangers they never dreamed of.

Lots of action and good characters as well as a world I don't want to live in. The twists and secrets go on. It is left open to continue the series.  Enjoy, it was hard to put down. ~~  Pam Allan