Bickering frenemies Meg and Shar are doing some serious damage at a midnight sample sale when they find themselves arguing over a pair of shoes—with fatal consequences. The girls are suddenly at the mercy of Hades—god of the underworld—who forces the teens to become Sirens, luring to the Underworld any individual whose unholy contract is up.

When Shar tries on a ring from Hades, it activates an obscure contractual clause that puts Shar and Meg in Hades’ service once more. Shar is whisked away to the Underworld to prepare a ball for Persephone, while Meg is sent to retrieve the errant soul of spoiled rich girl Paulina Swanson and send her to the abyss.