Cruel Bargain A Dark Apocalyps - L J Anderson

When the dead stormed the city, Britney was lucky to have her father to protect her and her sister. Too bad he let her down.

Sold to terrible men, she's learns just how depraved the world has become when she's forced to watch a young girl offered by the dead. But just as all seemed lost, giant men in black come to rescue them.

Unfortunately for Britney, they're no heroes.

After being taken to their base, an underground bunker called the Keep, she's immediately given to a man named Alistair, who demands to own her.

Initially, she resists his advances, but when she realizes the grave danger her sister faces, she makes a Cruel Bargain for the girl's rescue.