UNSEEN is a book in Karin Slaughter's Will Trent series. But two of the characters in this book, Sara and Lena, were originally in the Grant County series. Sara now practices medicine at a hospital in Atlanta and is Will Trent’s girlfriend. Lena is now a police detective in Macon, Georgia, which is where the story in UNSEEN takes place.

Will is an agent with the Georgia Bureau of Investigation (GBI) in Atlanta. For now, he is working undercover in Macon, trying to infiltrate a drug ring. Sara doesn't know where he is. Coincidentally, though, she comes to Macon when her stepson, Jared, who lives there, was shot numerous times during a home invasion. Also coincidentally, he is married to Lena, who Sara believes caused her former husband's death.

In addition to Lena's job as a detective with the Macon police, Jared is a motorcycle cop there. They don't know whether this has anything to do with the attempts on their lives.

Now Faith, normally Will's partner, is also working in Macon. As a GBI agent, she heads an investigation there at the request of the Macon police.

Will's undercover job, the attempted murders, and Faith's investigation are, really, one case. UNSEEN is full of twists and turns as Will, Sara, Faith, and Lena face what men will do for the money that comes from drugs.

I’ve read most of Slaughter’s books. As with every one of them, I did not want to see UNSEEN end. I guess that’s why it’s a good thing this is part of a series.