Vortex : an FBI thriller
(Book)

Series numeration from Goodreads.com.

"In the latest installment in Catherine Coulter's #1 New York Times bestselling FBI Thriller series, agents Sherlock and Savich find themselves dealing with powerful pieces of the past that could have dire consequences in the present. Seven years ago, Mia Briscoe was at a frat party with her best friend Serena when a fire broke out. Everyone was accounted for except Serena. She was never heard from or seen again. Now Mia is an investigative journalist covering the political scene in New York City, but she hasn't given up trying to find out what happened to her friend that night. When an old photo taken at the frat party gives her clues, Mia realizes she knows just where to look. She enlists FBI agent Sherlock's help to uncover a sinister string of events going all the way back to that disastrous party. But some very powerful -- and very dangerous -- people will do anything to keep the past buried. CIA Operative Olivia Hildebrandt is a team leader on a mission in Iran to exfiltrate a betrayed undercover operative. She's nearly killed by an exploding grenade and saved by a team member. After leaving Walter Reed Hospital, not only has that team member disappeared but two men come to her house to kill her. Savich believes their attack on Olivia is a direct result of the compromised mission in Iran. What intelligence was at stake? Who betrayed them? Savich quickly finds he is now a target himself and unseen enemies will stop at nothing, including murder." -- Provided by publisher.