Amazon.com description: Product Description: A Woman on a Mission 

The wagon train ride from Missouri to Kansas territory is rife with perils. But there are bigger obstacles for Dr. Victoria Fenway than cholera or creek floods. Years ago, she and wagon-train captain Joseph Rickard were deeply in love. Now, Victoria is tracking the man who killed her late husband, and she is determined to continue his work rescuing slaves. She can't allow herself to fall for Joseph again—not when he abandoned her once before. 

Joseph told Victoria he'd love her forever, and he's been as good as his word. Misunderstanding led to her marrying another man. But with dangerous slavers on their trail, he'll do anything to keep her safe until they reach a new home—and a second chance.