Lucius, a roman nobleman, travels to Thessaly and, while staying at the house of rich old miser Milo, begins a love affair with Milo’s slave Fotis after learning that Milo’s wife is skilled in black magic. One night Lucius convinces Fotis to sneak him into her mistress’s room and he watches as she transforms herself into an owl. Fotis takes a box of the potion she used to transform and gives it to Lucius, but when Lucius takes the potion he is turned into an ass (a donkey that is). Just then, Bandits break into Milo’s house and take the newly transformed Lucius with them as they escape. What follows is a series of misadventures, always violent and often sexual in nature, as bad luck seems to follow the Ass Lucius wherever he goes.