Justine, a virtuous young woman, faces a cascade of misfortunes as she is forced from a convent into a cruel world ripe with deceit and licentiousness. Alone and naive, she embarks on a journey seeking work, holding onto her belief in virtue and hoping for a future free of suffering. Her sister, Juliette, chooses a path of vice and quickly climbs the social ladder, becoming wealthy. Justine's unwavering faith in her morals is continuously tested as she encounters various corrupt individuals, including thieves and aristocrats who entice her into a labyrinth of depravity and power struggles.

The narrative contrasts Justine's virtue against the rampant vice she encounters, involving her in a series of unfortunate events that result from her interactions with several miscreants. Among them is the Marquis de Sade, an aristocrat with a twisted taste for pain and manipulation. As she navigates through these experiences, Justine's resilience is put to the test. She is faced with the option to either renounce her principles for the sake of comfort and security or persist in her righteousness despite the hardships. Her ordeals represent the tension between virtue and vice, creating a compelling examination of morality amid a society indulging in decadence and cruelty.