At the posh New Orleans home of wealthy Jason Foster, the servants disparage the arrival of Mr. Foster's relatives. Foster is in his upstairs bedroom enduring a visit from his doctor. They frankly discuss his imminent death, but Foster himself has plans to carry out and his determined to live until then.
The doctor is greeted by Mr. Foster's relatives downstairs. Emily, his long-suffering daughter, struggles with numerous perceived illnesses that she uses to try to gain attention. Her husband, Wilfred, is a callous businessman with no time for enjoying the pleasures of life. Vain granddaughter, Paula, barely takes time to look away from a mirror and dull grandson, Wilfred, Jr., is remarkably uninterested in anything.
The doctor candidly explains that Foster is dying before leaving. The family visit with Foster upstairs where he chastizes them for being so unchanging, his dry remarks revealing them for who they actually are. He tells them he's planned a dinner and a Mardis Gras party for just the family that evening, despite their hopes for something fancier.
That evening, he relates that he knows they have arrived, not to provide comfort to a dying man, but to start grabbing his possessions once he's gone. He reveals that he has indeed left them everything he owns, but they will only inherit if they agree to one demand: they must wear specially-made Mardis Gras masks until midnight.
The masks have been designed, according to Foster, to reflect the opposite nature of the wearer. Since his family members do not recognize their own flaws, they miss his commentary on Emily's mask reflecting selfishness while Wilfred's greed, Paula's vanity and Wilfred, Jr's cruelty are embodied in their own.
If any one of them removes their mask before midnight, the entire family inherits nothing. He will wear a mask with a skull on it to reflect death.
They endure for hours in the house wearing the stifling masks and arguing with each other when anyone wants to remove their mask.
As midnight arrives, Foster gives them one more chance to reveal something more about themselves beyond what is on the surface. When none will relent, he tells them their character flaws, but that, despite them, they kept their part of the bargain and are now rich.
As Foster dies, his family rejoices as they pull of their masks. Unfortunately, the hours of wearing them has caused their real faces to take on the features of the ugly, misshapen forms.
The death mask is removed from Jason Foster to reveal the peaceful, normal face of the bearer.