Season One follows the Bartlett-Fleming family, Grandpa Jack, teenager Amy and older sister Lou, as they deal with the ups and downs of running a ranch that's been in the family for generations but is now so deep in debt they're one back payment away from losing it all. After the death of their mother, the girls' lives change forever. Lou returns home from her high-powered job in New York to take over the business of the ranch. Amy realises she has inherited her mother's special horse whispering gift and is determined to keep her mother's dream alive by maintaining Heartland as a horse rescue centre. And Jack just wants to prevent the two girls from killing each other. Thrown into this mix is Ty, the hunky new stable boy; Mallory, the 12-year-old kid next door who never goes home; Scott, the local vet who had a thing for Lou back in high school; and Tim, the girls' estranged father, who has returned to Hudson and wants to reconnect with his family but doesn't know how.
Amy and Lou Fleming, and their grandfather Jack, deal with life after their mother's death while a new ranch hand, Ty Borden, comes to live and work at Heartland.
Lou sends an uncured horse back to its owner, which causes friction with Amy. Ty builds Amy a jumping ring and Jack decides to keep Ty on at Heartland.
Lou isn't pleased when a neighbouring rancher brings a pregnant mare named Melody to stay at Heartland. Ty is astonished when Jack asks him to join him on a cattle roundup.
Nick Harwell arrives to train Ben but becomes interested in buying Spartan. Mallory thinks Lou plans to re-home Copper and runs away with him, only to discover a plot to sell wild mustangs.
Amy finds herself working with the enemy when Ashley asks for her help. Amy's also preparing Spartan for the Fall Finale while Lou decides what to do about a job offer in New York.