The Heiress and the Cowboy: A Sweet Historical Western Romance (Caldwells of Rocky Creek - Book 1):

When Arthur Caldwell arrived in Billings, Montana, he was determined to only stay long enough for his meeting at the Northern Pacific Railroad office. He had plenty of work back on the Rocky Creek Ranch and was eager to return home. But when Mollie Bradstone announced he was her fiancé, his life took an unexpected turn. He needed to ditch this woman, but soon discovered this would be no simple task.
Mollie Bradstone witnesses a cowboy swoop a young child out of the path of an oncoming wagon...