Two brothers fleeing post-famine Ireland make a blood vow that neither of them will pass on the disease that has claimed so many of their Haggerty relatives. A chance meeting with the Brennan family, also on the way to catch a ship to America, tests that vow repeatedly as James Haggerty fights his growing attraction to the oldest daughter, Cat.

Through forty years of adventure and heartbreak, Cat refuses to let go of her childish dream of having a farm in Indiana, and of making James her husband. Following their lives in the Pennsylvania coal fields, through the Civil War and beyond, Cat Brennan's undying love for James Haggerty never waivers, despite bad choices they both make with their lives.