I Always Wanted to be a Spy - Barrett Judith A.

Librarian with the soul of a warrior.
Maggie Sloan survives an explosion and begins the slow healing process with the help of her unusual team. When a heart-wrenching murder shatters her world, Maggie's team trains her to fight to win, whatever the cost. Her grief and rage transform her from prey to relentless hunter, and her brilliant observational talents threaten a complex criminal scheme.

As Maggie closes in on the truth, she realizes she's on the trail of a mastermind, a dark puppeteer of serial killers, whose intellect threatens to match her own.

This gripping psychological thriller all comes down to kill or be killed.