In Horace Walpole's The Castle of Otranto, a series of calamities befalls Prince Manfred, and these misfortunes are presented as the just retribution of Heaven upon a usurping and tyrannical family. The evil that overtakes him is both supernatural and self-inflicted.
The curse upon a usurper. Manfred rules Otranto illegitimately, for his grandfather had seized the principality by poisoning its rightful lord, Alfonso the Good. An ancient prophecy declares that the castle and lordship of Otranto shall pass from the present family whenever the true owner should grow too large to inhabit it. The whole action works out this doom against Manfred's house.
The death of his son Conrad. The first blow falls on the very day Conrad, Manfred's sickly son, is to marry the princess Isabella. A gigantic helmet, matching that on the statue of Alfonso, crashes down and crushes Conrad to death. In an instant Manfred loses his male heir and the hope of continuing his line.
His tyranny and unlawful lust. Desperate for an heir, Manfred resolves to divorce his faithful wife Hippolita and to marry Isabella himself, the betrothed of his dead son. This monstrous scheme drives him to pursue the terrified Isabella through the castle and to behave with cruelty and violence, so that his own sin deepens the evil closing around him.
Supernatural warnings. Heaven repeatedly rebukes him. A portrait of his ancestor sighs and steps from its frame, gigantic limbs of Alfonso appear about the castle, and other portents warn Manfred of his approaching ruin, yet he presses on.
The killing of his own daughter. The climax of his misfortune is that, in the darkness of the church and mad with jealousy, Manfred stabs and kills his own beloved daughter Matilda, mistaking her for Isabella. His crowning evil is thus the destruction of his innocent child by his own hand.
His fall. Broken by grief and guilt, Manfred confesses the usurpation, surrenders Otranto to its rightful heir Theodore, and retires with Hippolita to a convent to spend the rest of his days in penance.
Conclusion. The evil that befalls Manfred, the loss of his son, the supernatural terrors, and above all the accidental murder of his daughter, is the working of divine justice upon a usurper. Walpole shows that tyranny and unlawful ambition bring ruin upon the guilty and end his corrupt line.