The Marriage Pact. The Vows, #1

Two rival families. One arranged marriage. A peace that could cost them everything. For twenty years, the Costa and Marchetti families have been locked in a bitter war. Now, with both sides desperate to end the bloodshed, Dante Costa and Serafina Marchetti are bound together in the ultimate peace treaty: marriage. Dante is the ruthless heir to the Costa family, with every reason to distrust the daughter of his enemy.
Serafina is intelligent, determined, and unwilling to become a pawn in a war she never started. Neither wants this marriage. Neither expects to fall for the person standing across the aisle. But when a deadly attack threatens them both, Dante and Serafina are forced to investigate together. Their search uncovers secrets buried decades ago-and evidence that the enemy may be hiding much closer than either family imagined.
As suspicion turns to betrayal and their carefully negotiated marriage becomes something neither planned for, they must decide whether they can trust each other before the fragile peace between their families collapses.