Have you ever dreamed of a better version of yourself?
Elizabeth, a fading star of the aerobics show, receives a mysterious offer to try a new, revolutionary product - "Substance". A cell-replicating agent that creates a younger, prettier and more perfect human copy. Once you start using it, you will only have to follow one rule - time sharing. Seven days for you, seven for the new version of you. Thus the attractive, youthful Sue is born. However, the existence of two women who share one consciousness soon begins to have unwanted consequences.