|First appearance:||Yang 3 in 2D|
|Last appearance:||Psych: The Movie|
In "Yang 3 in 2D", she is kidnapped by the returned Yin and held in a house. She escapes the house and goes to the police. There she gives Shawn a picture of him and Yang together. At first Shawn is the only one to believe that she was kidnapped by Yin.
Allison takes the detectives and Shawn to the house that she thinks Yin held her in. The team grows mad when they burst into a home where a family is sitting down to eat. She tries convincing the SBPD that she is telling the truth, but only Shawn and Gus believe her when she remembers the format of the first floor at the house blindfolded. Since Shawn is convinced Allison is telling the truth after that and her to his father's house for safety. There she is comforted by Henry.
Then, that night, Henry hears a crash and goes upstairs to find that she has been kidnapped, leaving the Yin/Yang symbol on the bed. Allison isn't seen until near the end of the episode where she is found by Shawn and Gus. They try to sneak her out, but then it is revealed that she has been Yin's assistant all along. She takes them, at shotgun-point, to Yin and tied them to chairs for him.
She then goes to talk to Juliet. She acts like she is still on her side, but fails when she tells Juliet that she had just woken up and doesn't know where Shawn and Gus are. Juliet figures out the truth after she asks Allison how she knew Shawn and Gus were at the house if she had just woken up. Allison then fights with Juliet, who won after both were bruised and scratched.
In the end, Allison is arrested. As she leaves, she stares at Shawn and Gus. Gus comments that he is going to be haunted by her in his dreams - and not in a good way.
Two-thirds of the way through the special, 'The Thin White Duke' is shown to be a stalking horse for Allison's revenge fantasy, and one that she needed to put down. She then proceeds, in true supervillain style, to soliloquize on her motives and plan, before handing the gathering of heroes over to her assembled assistants.