Out of the Ashes by Chloe Parker

Callisto’s streets are full of ghosts. And for smart-mouthed mercenary Baz Vaughn, those ghosts are coming back with a vengeance.
Framed for the murder of his parents in a bloody massacre, Baz escaped his home moon of Callisto twelve years ago. Since then, he’s been on the run from his vengeful brother, the undisputed king of Callisto’s underworld. Baz was happy to traverse the galaxy, working as a soldier of fortune on distant planets and moons.
That is, until he met Tasha Kincaid and fell in love.
Now, he’s headed back to Callisto with Tasha to find the sister she lost a decade ago. Baz knows that Callisto isn’t safe, but he fears letting Tasha go it alone. The two discover that their siblings are married themselves, and Tasha will have to go directly into the lion’s den to rescue her sister from Baz’s crime lord brother.
Even worse, Baz’s psychotic ex – a deadly assassin – is stalking him through the city’s streets, and she won’t let him go again.