As Amy's sweet sixteen approaches, new hand Caleb is interested in asking her for a date. Amy is fascinated with the white mustang that's lost his herd but has been spotted around Heartland. Meanwhile Lou and her dad are working on plans to start an "Equine Executive Retreat" but Grandpa Jack is none too thrilled with the idea of an upscale dude ranch on his property. Mallory is lobbying to spend the summer at Heartland while her parents travel with the rodeo. And Ty's not been heard from since he left for the city to get reacquainted with his father.