None - The town of Hudson in the Rocky Mountains is home to Heartland, the Bartlett family ranch.  When his daughter Marion is killed in a car accident, Grandpa Jack is left alone to run the ranch with his two granddaughters, the fiery teenager Amy and her ambitious sister Lou.  But the family is so deeply in debt that they might end up losing Heartland.  Tough and practical, Lou leaves her life in New York City to take over the business of running the ranch.  Her rational approach creates friction with the sensitive Amy, who has inherited her mother's gift as a horse whisperer and is determined to keep her mother's dream alive.

Asid from horses, Jack now has two granddaughters to reign in.  Luckily he has help from Ty, a tough and rebellious young man who was able to avoid jail by doing time on the ranch instead, Mallory, their 12-year-old neighbor, and Scott, the local veteranarian, who has both a thing for Lou and a way with horses.  But Val could be trouble; the weathy widow and owner of a nearby ranch, she has her eyes on Jack...and perhaps Heartland as well.  Although ups and downs divide them, nothing brings them closer than their passion to save their dream, Heartland.