Hannah Webster was shrewd, charming, and ruthless. Once head of Allan Pinkerton's Female Detective Bureau, she was now a fugitive from justice and a woman bent on revenge. Dismissed from the Pinkerton Agency when her former protégé, Amanda Brown, exposed her collusion in President James Garfield's recent assassination, her only interest apart from self-preservation was to see Amanda punished.
Eager to rebuild her lost fortunes and thus finance Amanda's downfall, Hannah makes plans to exploit the rampant speculation in Mexican Southern Railroad's proposed spur line to America. Pursuing the demands of her clever investment swindle, Hannah travels south of the border, unaware Amanda is already there. Sent by the Pinkerton Agency, with her partner, Christopher Garrety, to settle a volatile labor dispute between Mexican Southern and is competitor, Nordeste Railroad, Amanda's investigation soon converges with Hannah's private interests.
Determined to stop one another, Hannah and Amanda's private war is swiftly disrupted by a new and unexpected menace, demanding retribution of his own for a past betrayal. Swept into a high stakes game of cat and mouse, neither can hope to survive alone. Only fate could determine which woman must pay the ultimate price for revenge.