From daunting high-energy choreography to nine-hour prosthetic application, the stars tell EW "The Substance" was a satisfyingly grueling, months-long shoot.

The Substance, the new film starring Margaret Qualley and Demi Moore, has set a record for the latter. The body-horror film follows a fading celebrity (played by Moore) who begins to use a black-market drug that creates a younger version of herself (Qualley).