The Apprentice: (Rizzoli & Isles series 2) by Tess Gerritsen
The Surgeon has been locked up for a year but his chilling legacy still haunts the city, and especially Boston homicide detective Jane Rizzoli. But now a new killer is at work and Rizzoli senses something horrifyingly familiar about this murderer's modus operandi. It's when the FBI starts taking an interest in the investigation that Rizzoli begins to wonder just what makes this case so different, so dangerous that the Feds feel the need to get involved. But then the unthinkable happens: the Surgeon escapes. And suddenly there are two brilliant, twisted killers on the loose - master and apprentice, united in their hunt for the most challenging prey of all: the very woman who is hunting them.