On the same day, thirty-year-old Cassie discovers she's pregnant and learns that her husband, Ryan, is unfaithful. She hides the fact that she knows about the affair, and the more he hides it, the more enraged she becomes. Cassie starts slowly poisoning her husband when she learns he's planning on leaving her. Over a few days, Ryan becomes so sick he can't move. Cassie keeps him in a semi-conscious state and decides she likes the control she has over him.
Cassie's mental state quickly deteriorates, and when she has a spontaneous affair with an old friend, she starts to believe she can make Ryan disappear and start a family with her new lover. When Cassie tells him she's pregnant and he's the father, his reaction isn't what she expects. When the police and Ryan's family start to become suspicious, her mental state deteriorates into a series of irreversible decisions.