Villains Are Destined to Die: vol. 6

Following the conditions of a contract between herself and Winter, Penelope is once again leaving the duchy! She joins the marquis for volunteer work in a war-stricken nation, and while their time there is hectic, the two are able to grab a moment alone at the seaside. But the couple's peace is shattered when they learn sorcerer children have been kidnapped! In the face of Penelope's desperation to save them, Winter's calm approach to the situation has the duke's daughter suspecting that everything is not as it seems...

Translated from the original Korean (which makes this manhwa, rather than manga!)