Julia Banks has just completed a messy divorce and is eager to start anew with her fiancé, David Connover, and his young daughter, Lily. Moving into David's home, she attempts to integrate herself into her new life, which is complicated by the presence of David's ex-wife, Tessa. Tessa, still grappling with the dissolution of her marriage and feeling replaced, exudes an air of control and perfection that hides her obsessive tendencies. Julia finds herself increasingly unsettled by Tessa's intrusive behavior, which begins to border on harassment. Tessa's efforts to undermine Julia escalate as she executes meticulously calculated plans to sabotage Julia’s relationship with David and manipulate the lives of those around her.

As tension builds, Julia becomes more isolated and paranoid about Tessa's true intentions. Tessa's manipulations stretch beyond passive-aggressive tactics; they become dangerous and intensely personal. The situation unravels quickly as secrets from Julia's past are unearthed, fueling Tessa's vendetta. With growing mistrust clouding their interactions, Julia struggles to prove her innocence and maintain her relationship with David amidst the orchestrated chaos. The plot thickens with psychological mind games and suspenseful cat-and-mouse dynamics until the culminating confrontation between the two women forces the characters to face their deepest fears and motivations.