Hannibal by Thomas Harris

Hannibal is a novel written by Thomas Harris, published in 1999. Hannibal is the third in his series featuring Dr. Hannibal Lecter, the cannibalistic serial killer, and the second to feature FBI Special Agent Clarice Starling. The novel Hannibal takes place seven years after the events of The Silence of the Lambs and deals with the intended revenge of one of Hannibal Lecter's victims. Hannibal was adapted as a film of the same name in 2001.
Seven years after rescuing Jame Gumb's last victim, Clarice Starling witnesses her career crumble around her when a drug raid goes wrong and she kills an armed meth dealer named Evelda Drumgo, who was carrying her child at the time, in self-defense. Hannibal Lecter, who has been living in Florence, Italy, under an assumed name since escaping custody, sends her a letter of condolence. Desperate to catch Hannibal, the FBI finds a use for Starling once again. She meets with Barney Matthews, former orderly of Baltimore State Hospital for the Criminally Insane. He tells her what Hannibal said about her and that he said he would never go after him if he escaped.
Mason Verger, a wealthy paedophile who was left horribly disfigured after a "therapy session" with Hannibal, plans to exact gruesome vengeance against Hannibal, using Starling as bait. He wants to feed Hannibal Lecter to pigs and videotape it. He is aided by corrupt Justice Department agent Paul Krendler, Starling's personal nemesis.. (Summary by Wikipedia)