When Natalie's boyfriend is murdered, she builds a machine to change the past by changing her own memories. She discovers she can re-experience the moments in her life, but changing those moments proves to be harder than she thought. An FBI agent, her sister and her therapist all try to stop her before she hurts herself, but there's no use. She'll do anything to get him back and she fights through setback after setback in her effort to reunite with the deceased love of her life.