Thirteen Days in Milan. Milan DIGOS Thriller Series, #1

Sylvia de Matteo, an American single mother, is taken hostage by terrorists during a political assassination at Stazione Centrale, Milan's train station. She is seized at gunpoint and thrown into the back of a van. Moments later, a Paris-bound train with Sylvia's fiancé and ten-year-old daughter aboard departs Centrale without Sylvia. The terrorists drive Sylvia to a warehouse where she is imprisoned in a cell.
When the terrorists discover Sylvia's father is a wealthy Wall Street investment banker, they demand a ransom for her safe release.