Brilliant scientist Linnea Newberry is on the adventure of a lifetime, traveling the Santa Fe Trail with her grandfather, Dr. Powell, on a botanical expedition to Colorado Territory. She longs to be taken seriously by the other team members, but at every calamity she faces, her grandfather threatens to send her home. After watching his ma suffer and die in childbirth, Flynn McQuaid has sworn off women and marriage forever. Headed west to start a new life, he has his hands full not only taking care of his younger siblings but also delivering cattle to his brother. He doesn't need more complications. When Flynn rescues Linnea from drowning during a river crossing, Dr. Powell promptly hires Flynn--unbeknownst to Linnea--to act as her bodyguard for the rest of the trip.

As Flynn fights against the many dangers of the trail, he soon finds himself in the greatest danger of all--falling for a woman he's determined not to love.