The air in Vienna was brittle, sharp with the cold breath of winter even though spring lingered on the horizon. Ancient buildings, their stonework kissed by centuries of history, stood unmoved while the present waged quiet war in their shadows. Beneath the cobbled streets and opulent façades, a war room thrummed to life in the basement of an abandoned opera house.

Emma Carter stood before a holographic map, her arms folded, eyes fixed on the blinking red indicator above the Austrian border. ...