Alice Cassity was the oldest sibling of the Cassitys, a family that came into great wealth through dubious means.
Alice Cassity lived on her family's land in Shoshone, Idaho with her husband Carl Granville. Sam and Dean Winchester arrived there because they were in search of a hellhound to kill in order to satisfy the first of the Trials. They were fairly certain that since the family's wealth came from oil being struck on their land where no oil had ever been detected before, it was likely that a crossroads deal had been made by someone in the family. They decided that since neither Carl nor ranch manager Ellie have any ownership in the land, Alice was the most likely candidate to have sold her soul.
Later, as Alice and Carl were enjoying a romantic candlelit dinner, they heard what sounded like wolves howling in the distance. Alice left the table to check on her horses, and Sam and Dean followed her, armed to dispatch the hellhound. Back at the dinner table, Carl was attacked and killed.
As it appeared that they had guessed wrong about who made the deal and had missed their chance to complete the first Trial, a frustrated Dean was ready to pack up and start searching for another chance. Sam found Alice in the stable and asked if she was okay. She seemed amazed that she felt fine even though she had loved Carl, although she could not remember why. Sam was confused, and she explained that they had grown up in the same town, and even though he had always mooned over her, she had never really given him the time of day; she even used to make fun of him. At a party on Valentine's Day in 2003, she saw him in a new light and magically fell in love with him. After ten happy years together, she was not angry or even sad.
Sam went back to their room to find Dean packing and making plans to summon a Crossroads demon to force it to call a hellhound. Sam explained that Carl had not sold his soul for the oil, he had sold it for Alice. He talked Dean into staying to scope out all of the family members who were going to arrive for Carl's funeral, as he thought it had to be one of them that had made a deal for wealth.
Later, Margie was attacked and killed after she and Noah drunkenly marched into the woods intending to track and kill the "wolf" that killed Carl. Sam was standing guard over the surviving family members after he and Dean put them on lockdown, and demanded that the one who had made the demon deal should reveal themselves. As Cindy and Noah accused each other, Alice realized that it was Margie who had sold her soul, remembering that Margie used to say that if they were rich, they would all be happy.
Alice subsequently got out of her cuffs when Sam had his back turned and attempted to get to her car, but Sam managed to stop her. They then spot the hellhound, so Sam ushers her back inside. Once the hellhound is killed, Alice and her family are released.