Amy is a 15-year-old girl growing up in Hudson, Alberta with a serious love of horses. She discovers that a horse named Spartan is being abused at Mallen's farm and convinces her mother, Marion, to rescue him. A storm on the way home sends their truck and trailer off the road and onto a steep hill, crashing into a tree. When Amy wakes up, she's in the hospital and discovers that her mother died in the accident. Amy's sister Lou comes home from New York City to help. Refusing to put Spartan down, Grandpa Jack brings the horse back to Heartland hoping that Amy can help him. Before Amy can help Spartan, she has to come to terms with what happened to her mom. The new ranch hand, Ty, starts working and he was hired by Marion before she died.

Lou accidentally sends home Mrs. Roach's horse despite the fact that her horse's fear of vehicles has yet to be cured, after misinterpreting Amy's description of the horse as "fine." Val Stanton begins spreading rumors about Heartland and their inability to be successful without Marion. Ty's probation officer comes to the ranch while he is off showing Amy the jumping course he made for her in the woods. Jack agrees to be Ty's sponsor in place of Marion.

Heartland has its first "Open House," and Lou invites her and Amy's estranged dad Tim, who accepts the invitation. Amy works with world-famous horse breeder Lisa Stillman's horse, Promise, who seems unusually aggressive when saddled. Val Stanton challenges Amy, saying that the horse is drugged to appear calmer. Amy proves her skills by fixing the problem that Val's expensive horse is having with jumping. Jack kicks Tim off of the property when he discovers him in the barn. Pegasus is depressed because of Marion's death.

When Amy and Lou empty their mother's room, they find a letter dated seven years previous, from their father. Ben Stillman is sent to live at Heartland by his aunt, Lisa, while she's in France. No one likes Ben, as he uses methods like whipping his horse, Red, to show him "who's boss", and he doesn't participate in ranch duties. Ty is especially angry, challenging Amy to prove that Heartland is different than the other stables (like Briar Ridge) that tolerate this treatment of horses. Amy gets knocked off her horse while trying to take Ben's horse across the river on a trail ride and sustains a minor head injury. Ty is offered a job at Briar Ridge even after Amy accidentally tells Ashley that Ty is on probation. When Amy hears that Ty might take the job, she snaps at him. Ty is eventually fired when Val discovers he has a record.

Lou upsets her friends and family as she arranges to have a video made to promote Heartland and micromanages its filming. The video eventually airs on TV after the news and is popular with viewers, dramatically increasing the number of calls Heartland receives for help with troubled horses.

Lou's New York boyfriend Carl comes for a visit, but his big city attitudes clash with the ranch's more laid-back lifestyle. Lou discovers that she has been fired from her job in New York. Carl proposes to Lou, but she discovers he has been trying to force her to move with him to Chicago. Amy is puzzled why a new horse at Heartland called Pirate won't obey commands. Scott unearths the horse's unusual past.

Heartland takes in a pregnant mare named Melody. Ty secretly asks Mallory for riding lessons to impress Amy. Ben competes in a horse show and refuses to talk to his aunt Lisa. Meanwhile, Jack and Ty go on a cattle round-up, and Tim is introduced as the trail boss. Jack and Tim fight each other that night, and Ty learns that Tim is Lou and Amy's father, and Jack's ex-son-in-law. Lisa shows up to talk to Ben, and Jack invites her to stay for pancakes.

Amy tries to help a champion stallion and his depressed trainer, who were injured in a stable fire. In the process, she confronts her own unresolved feelings about her mother's accident. She is also able to clear the name of the trainer, who had been blamed for the stable fire and consequently lost his job. Meanwhile, Jack grows increasingly attracted to Lisa. She asks Jack to come look at a horse with her, and he agrees, but insists on driving his truck to the sale. Jack declares that it's not a date but it turns into one, especially as they share a picnic lunch when Jack's truck breaks down. Jack and Lisa enjoy themselves, until Dan Hartfield shows up at the sale and introduces himself as Lisa's husband. Jack leaves her behind, feeling foolish, until Lisa shows up later at Heartland, and explains that Dan is actually her ex-husband.

After elderly Mrs. Bell has a heart attack, Amy takes in her Shetland pony Sugarfoot, to whom Lou grows surprisingly attached. Lou reminisces about learning to ride on Sugarfoot when she was young, and singing to him with Mrs. Bell. Ty's old girlfriend, Kerry Anne, from his past group home shows up looking for him, having taken a job in the kitchens at Briar Ridge. She manages to cause her fair share of trouble in the process, ripping off Soraya and stealing from Ashley, as well as creating friction with the Heartland family. Amy initially feels threatened by her, but Ty sends Kerry Anne on her way to BC, knowing that she is bad news.

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.

Tim's visit to Heartland causes sibling rivalry between Lou and Amy. Jack takes Lisa Stillman fishing on their second date.

Disaster strikes when the barn erupts into flames and Jack's badly hurt getting the horses to safety.

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.