This note contains spoilers for the book.

Amazon claims, apparently falsely (no actual book found, no confirmation on Sandford's web site), that this is the second in a series.

An outside investigator / fixer is employed by the White House to figure out what's going on with the disappearance of a Senator and surrounding weirdness.

There's quite a lot of the surrounding weirdness. Gay politician, connected to large insider gay group (naturally). Military members and veterans working in various security roles. Attraction between the investigator and the probable widow.

And, not too horrid or nasty. No really a well-defined antagonist, either.

Turns out to be the Senator found he had cancer, and set up something intended to look like an abduction and murder to create support for some of his positions. However, the need to hide the head (so the autopsy won't find the cancer), for example, was a problem from the beginning. And the use of a phone book to slow down the slug so it remained in the body was fine, but also guaranteed to be obvious to forensic analysys. Apparently the conspirators in this book didn't watch CSI.