It's just a bad period.

Agnes Applewhite, a blossoming young woman caught between her sanctimonious mother and tightly wound sister, defies her family’s expectations by taking a job as a shampoo girl at a lively beauty salon. As she thrives in this new colorful world, she is suddenly confronted by debilitating menstrual cramps that become real-life monsters, blurring the line between reality and nightmare.