When Amy bravely tries to heal an abused (and now extremely violent) racehorse Ty and Jack think she's finally bitten off more than she can chew. Meanwhile, Miranda shows up to bring Shane home early when she learns what her son's been up to on his summer vacation with Tim. Peter and Lou are at odds with Lisa over their plans to start building their home near the Dude Ranch. And Jack has his own issues with Lisa to deal with when he finds out she's been spending time with her ex-husband, Dan.
Ty's mother Lily returns to Heartland with shocking news about his father, and a secret that threatens her relationship with her son. Meanwhile, Amy continues to work with Alcatraz and enlists Lily's help to get the horse to trust people again. And when Lou finds herself without a babysitter, she is forced to take an important client meeting at Heartland.
When Jack learns Ty is riding his bike solo to a remote lake to spread his father's ashes he decides to surprise Ty and join him for this meaningful road trip. Amy is hurt by Ty's decision to make the trip without her and throws herself into helping Bryce, the paralyzed exsoldier we met in season 4, to find a new horse suitable for para-riding. Mallory is totally conflicted when Austin tries to woo his way back into her life. And Soraya has a new boyfriend that could mean big changes in her future.
In an attempt to avoid hitting a wolf, Ty is badly injured when he crashes his bike on a remote road leaving Jack to search for help in the middle of nowhere. Meanwhile, back at Heartland, an anxious Amy has visions that tell her something has happened to Ty. When his lawyer digs up some dirt on Miranda, Tim starts thinking seriously about a custody suit. And Lou and Peter both receive interesting career opportunities that complicate their parenting plan.
Amy is roped into helping Tim project a positive image to the community, in hopes it will further his custody case for Shane. Meanwhile, Ty works to restore his bike, and his shaken confidence, so he can get back on the road. Lou and Lisa come to a crossroads in their business partnership when construction finally begins on Lou and Peter's dream home at the Dude Ranch... during peak season! And Caleb returns from Vancouver with his and Ashley's future finally settled.
When tragedy strikes Amy must find a way to save Mr. Hanley's rescue horses from kill buyers. Meanwhile, Tim makes an impulsive decision that he thinks will grant him custody of Shane. Lou and Peter can't find a house that stacks up to Lou's incredibly high standards. But in true Lou fashion she unwittingly finds herself in a bidding war with Mrs. Bell and Mallory is caught right in the middle.
Amy and Ty join Scott on a trip back to his old reservation to save a herd of wild horses from the dangerous EHV-1 virus. While there, Scott must deal with some unfinished business from his past. Meanwhile, Mallory's plans for the perfect sweet sixteen party are interrupted by some life-changing news. And Tim's tumultuous custody battle for Shane and recent break up with Janice send him down a dark and familiar path.
When Amy's dog Lobo is injured by a trigger-happy rancher, it's up to Ty to save his life. Meanwhile, Mallory hatches a wild plan to avoid the move to Nashville. And Jack convinces Miranda to return to Heartland to deal with Tim's increasingly erratic behaviour.
When a mystery horse arrives at Heartland, Amy and Ty are sent down a path that will alter their lives. Meanwhile, Tim and Miranda realize they have to take their son's wishes into consideration, so they decide to spend some quality time together with surprising results. Peter drives Lou crazy when he takes over the plans for their second anniversary celebration but she is almost speechless when he reveals his surprise.
Amy is bursting to ask Ty about the engagement ring, and why he hasn't proposed yet, but a couple of 'runaways' throw everything at Heartland into turmoil. Meanwhile, as Lou tries to keep it a secret that she knows about the ring, she and Peter must also cope with the money pit that the Hanley Farm renovation has become. Lou is under so much stress that when things start to go missing around Heartland, she thinks she's losing it. And Ty finds an unexpected surprise in the barn that could change the entire Fleming-Bartlett family dynamic.
When Ty needs some engine parts for his broken down truck he's forced to turn to the last person on earth he wants help from - his stepfather, Wade. Meanwhile, Lou goes after the financial portfolio of Lisa's wealthy ex-husband (Dan Hartfield) and learns something that could be devastating to Jack. Amy works with a miniature chuckwagon horse and discovers he may have a greater calling. And Georgie and Mallory need to put aside their differences to pull off a special dinner at Heartland.
A trip to help out an old friend at a fishing camp doesn't go as planned, and a series of unexpected events elevate it into a life-changing weekend for the entire family. Amy and Ty wind up going to the camp on their own, where a shared adventure involving a wounded foal brings them to a special moment. Meanwhile, Georgie realizes too late the real reason she and Jack have had to stay behind while Lou finds herself swamped with a flu-stricken Katie. And on top of everything, Jack and Lisa's issues come to a head.