Edmea is an orphan in love with Count Oberto, whose father disapproves.
In Oberto’s absence Edmea is forced to marry the servant Ulmo, who is also in love with her, but with the loss of Oberto, Edmea is driven mad and tries to kill herself by jumping into the river.
She wanders the countryside with Ulmo who continues to love her and pretends to be her brother.
They join up with a band of jesters and with them return to the castle where Oberto has been mourning his loss.
On recognising Edmea, Oberto’s declarations of love help her to regain her reason.
Ulmo makes the ultimate sacrifice, shooting himself, so that Oberto and Edmea are finally able to celebrate their marriage.