The Silver Wolf: James Ryker, Book 3

Ex-intelligence agent James Ryker sets out on a revenge mission that takes him from the crystal waters of Mexico's Caribbean coast, right back to his country of birth, England. Once there, he stumbles upon a terrorist attack targeting his old employers. All the clues point to The Silver Wolf. But just who is he, and why is he hell bent on punishing not just Ryker, but his closest allies?