She is portrayed by Alison Tolman.
To earn extra income, Mary Pat joins Secret Shoppers, a seemingly harmless business formed by Beth Boland, Ruby Hill, and Annie Marks. However, due to her busy schedule and looking after her three children, she fails to successfully do the tasks assigned to her. She is subsequently fired by Beth, Ruby, and Annie but soon realizes that the business is associated with organised crime. She begins to blackmail the ladies to force them to pay her $10,000 a month in exchange for her silence.
She later meets and starts dating Boomer until she learns that he manipulated meeting her so he can expose Annie's crimes. From Beth, Mary Pat also learns that Boomer attempted to rape Annie. However, the two later became engaged as Boomer threatened to tell Jim Turner about Mary Pat's affiliation with the three women.
When Mary Pat plans to escape, Boomer rapes her. While Boomer sleeps, Mary Pat decides to leave with her children but he tries to stop her minivan and gets hit in the process.
Described as a "wolf in sheep's clothing," Mary Pat seems like a down-to-earth mother and breadwinner of her three young children. The lengths she would go to provide for her family will later reveal her as a blackmailer capable of fraud and other crimes.