The opera uses a slightly revised version of the 1701 Italian libretto by Apostolo Zeno that was based on Giovanni Boccaccio's The Decameron (X, 10, "The Patient Griselda").

[2] Years before the action begins, Gualtiero, King of Sicily, had married a poor shepherdess, Griselda.

Now, faced with another rebellion from the Sicilians, Gualtiero is forced to renounce Griselda and promises to take a new wife.

She is in love with Corrado's younger brother, Roberto, and the thought of being forced to marry Gualtiero drives her to despair.

Gualtiero foils an attempt by Ottone to kidnap Griselda and allows her back to the court, but only as Costanza's slave.