The royal House of Salina is one of the most important families in… well… the country doesn't really exist anymore. And why doesn't it, you ask? Well that's what The Leopard is going to help us find out.
The novel's main character is Prince Fabrizio di Salina, a huge, quick-tempered guy who knows that his family will soon lose all of its prestige and wealth. He takes a walk around his house and remembers seeing a dead soldier in his garden a little while earlier. The death seems pretty meaningless to him, but everybody already knows that there's no way Sicily is going to fight off the invading forces from Italy. To get his mind off the troubles, Fabrizio hits the town of Palermo to visit his mistress and have a general good time.
After some Italian soldiers land in Sicily, the Salinas hightail it out of town and go stay at their country home in Donnafugata. While they're hanging out there, Fabrizio's nephew Tancredi falls in love with the local mayor's daughter, Angelica. This devastates Fabrizio's daughter Concetta, who's also in love with Tancredi. Tancredi and Angelica become engaged. Meanwhile, Italian troops take over Sicily and hold a rigged public vote to show that everyone in the town wants to join Italy.
Later in the book, Lampedusa gives us every sexy detail about the young romance between Tancredi and Angelica. The two of them like to wander through all the secret rooms of the Salinas' old house and make out whenever possible. But as far as we know, they never give into their sexual urges before getting married. In a different part of the house, a foreign minister shows up and asks Prince Fabrizio if he'd like to become a senator in the new United Kingdom of Italy. Fabrizio's not interested though because the job would actually require him to do some work for his money.
Lampedusa is a big fan of side plots, which he shows us when the Salinas' family friend, Father Pirrone, leaves the Salinas to visit his home village. While there, he has to find a way to get his nephew to marry his niece because the niece is pregnant with the nephew's child (yeah, they didn't really cringe at kissing cousins back then). Once he's done that, he returns to the Salinas. Later on, the Salinas attend a ball at the house of one of their aristocratic buddies so they can talk about all the latest monocles and top hats. It's here that Angelica is first presented as Tancredi's bride-to-be. Everyone goes nuts over how gorgeous she is. But Prince Fabrizio can only think about how old he's getting and how little he'll leave behind when he dies.
The book flashes forward sixteen years to when Prince Fabrizio is dying of old age. He's every bit as gloomy. But in his final moments, he sees a beautiful, angelic woman standing near his bed, and he knows that death will bring him a sense of peace that life never could. Once he's gone, the book switches to his daughters, who are all past seventy. The final chapter of the book shows a religious official visiting their home and throwing out a bunch of old relics and artifacts from their personal chapel. The book ends with Fabrizio's daughter Concetta looking out her window and thinking she sees a leopard (the Salina family symbol). But it's only an old stuffed dog being thrown into the garbage. How's that for some crushing symbolism?