Phoebe makes a promise to her dying mother to take care of her younger sister Grace, no matter what. Even if that means travelling hundreds of miles across the country in a wagon train bound for Oregon. Phoebe suspects the uncle who is now their guardian had a hand in their father's death, and she knows she must get Grace away from his evil clutches before it's too late. Colton Wallace has been hired to lead a wagon train and doesn't have time to deal with anyone who isn't prepared for the trip. When a young boy shows up with his younger sister in tow, he knows immediately it's a woman standing before him. She says she's the sister of his closest friend, and she needs his help to get to Oregon where her brother will catch up with them. Two young women alone on a wagon train is too tempting to anyone who might take advantage of them, so he agrees to take them only as long as Phoebe continues her charade of being a man. As the miles roll away under the wheels of the wagons, Phoebe realizes the dark-haired man who'd appeared so gruff when they met, now always seems to be there to help when she needs him. They will face many miles together, enduring serious hardships that will test not only their strength, but the love that begins to develop between them along the way.