In Dark Descendant P.I. Nikki Glass finds out that she is a descendant of Artemis, Greek goddess of the hunt. When she finds out that part of being a descendant means that she is now immortal, her life is thrown in to turmoil. Anderson, leader of a small group of immortal descendants, contacts her to help him hunt down his wife Emma, who was kidnapped by the Olympians, immortal descendants of Greek gods.
Deadly Descendant is what happens after the end of Dark Descendant. Emma is back, but after ten years of being held captive, she isn't quite right. Emma and Anderson are constantly fighting and Emma is doing all she can to drag Nikki in to the middle of the fights.
On top of this the Olympians have come to Anderson for help, civilians are being attacked by an immortal descendant of Anubis. Nikki is on the hunt with the help of Jamaal, descendant of Kali (Hindu goddess of time, change, and death) and Jack, descendant of Loki (Norse god of mischief) along with several others. Nikki is in a race against time since the killer has a schedule and an agenda.
I would give this book a 4 out of 5 with a warning that this book does contain sexual situations and of course violence. The Nikki Glass series seems to be geared more towards adults, unlike Jenna Black's other series Faeriewalker.
Dark Descendant by Jenna Black - I would recommend reading the first book first. These are not stand along books, to get the full affect you need to read them in order.
The Devil Inside by Jenna Black - If you liked this series, you might want to try out some of Jenna Black's other books, this is another of her adult series.
The Lightening Thief by Rick Riordan - I know I recommended this one before but it is fitting yet again, this is a teen version of being the descendant of a god.