In The Substance, the career of former actor Elisabeth Sparkle (Demi Moore) is diminished to daytime aerobics instructor on a television network. On her 50th birthday, she is made redundant by a network executive, Harvey (Dennis Quaid), who tells her “renewal is inevitable”. There is no future for ageing women. In her redundancy, Elisabeth has an accident. At the hospital, she is passed a note from a handsome young doctor for a black-market drug known as “the substance” that promises to generate a younger version of a person with a single injection. Desperate for youthful relevance, Elisabeth takes the substance…