Blindside.
(Book)

When New York City's Mayor is desperate to find his missing daughter, Detective Michael Bennett steps in to help the Mayor and strike a deal to save his son in prison.
Bennett and the mayor have always had a tense relationship, but now the mayor sees in Bennett a discreet investigator with family worries of his own. Just one father helping another.
The detective leaps into the case and sources lead him to a homicide in the Bronx. The victim has ties to a sophisticated hacking operation—and also to the mayor's missing daughter, Natalie, a twenty-one-year-old computer prodigy. The murder is part of a serial killing spree, one with national security implications. And suddenly Bennett is at the center of a dangerous triangle anchored by NYPD, FBI, and a transnational criminal organization.
Michael Bennett has always been an honorable man, but sometimes—when the lives of innocents are at stake—honor has to take a back seat. Survival comes first.