Il Novello Giasone is based on Giacinto Andrea Cicognini’s Giasone, the most performed opera in Italy during the 17th century, set to music by Francesco Cavalli for the Venetian Carnival of 1649. Giovanni Filippo Apolloni reworked the text, shortening it or rewriting it in places, in collaboration with Filippo Acciaiuoli. Published in 1671 in Rome, the text is introduced with a dedication to Marie Mancini. It was either performed on Cavalli’s score, modified by Alessandro Stradella, or, according to some sources, on music by Acciaiuoli himself. This is likely the version that Acciaiuoli staged in 1678 with puppets at Princess di Sonnino’s palace, for the French ambassador.

Besides shortening the libretto of Giasone and removing large choirs, this text adds several stage directions detailing the action and where it is set (a cave, a labyrinth). Instead of the dance of seamen in Cicognini’s version, the interlude between the second and the third acts is a dialogue between a satyr and Amore (Eros): the satyr throws stones at Amore to drive him away, leading to a flying scene during which a dance of “Amori grandi" joins Amore.

Combining many sources, the action of the text moves from one place to the next, in keeping with the tradition of the dramma per musica: within a single act, the scene goes from Colchis to the island of Lemnos and then to the mouth of the Ebro. The play uses all the key elements of baroque theatre: a scene of magic, a dressing-up scene and a scene of sinking play one after the other, continuously alternating between a heroic and a comic tone. This comic tone originates in characters with strong features, such as a Demo, a boastful hunchback who stutters, Delfa, an aging visionary, Besso, a soldier who refuses to kill more than one queen a night and swears that he is a soprano, and Alinda, a woman who goes from lover to lover. However, the comic dimension also extends to characters associated with loftier theatrical tones: Oreste (Orestes) turns out to be an opportunist, capable of stealing kisses from Isifile (Hypsipyle) while she sleeps; Egeo (Aegeus) dresses up as a seaman, meets Demo in a night scene and is taken for a hairless, hornless, tailless demon; Medea herself also proves that she can act like a comedy shrew, driven by envy. In fact, the sense of comic runs through the entire play, insofar as Giasone (Jason) finds himself between two women, both claiming him as their husband; this is reminiscent of Molière’s Monsieur de Pourceaugnac. The melodramatic plot of the victim making a mistake is thus mitigated, and the baroque feast helps put an end to everyone’s hatred with songs.

In the Prologue, Sole (the Sun) and Amore (Eros) compete over Giasone (Jason), to settle which woman, Isifile (Hypsipyle) or Medea, he will love.

In Colchis, Giasone forgets himself in Medea’s company. His friend Ercole (Hercules) reproaches him for his lack of heroic diligence. Indeed, the hero left his first wife, Isifile (queen of Lemnos), to find the Golden Fleece, and he declares his love to his new mistress. As for Medea, she dismisses Egeo (Aegeus), whose love bothers her. Oreste (Orestes) came to inquire about Giasone on behalf of Isifile; he meets the stammerer Demo, who challenges him to a duel and then begs to be his friend, while still imploring him to let himself be beaten because it would make Oreste happy. Medea plays with Giasone and makes him believe that she wants him to marry Delfa, then she declares her love to him, causing bitterness on the nurse Delfa’s part. While Isifile laments the loss of her husband, Medea wards off the spirits to ensure Giasone’s success in his quest for the Fleece.

Oreste learns about Giasone’s love for Medea and goes to tell Isifile, whom he finds asleep, dreaming about her husband’s return: he takes advantage of the situation and steals a few kisses from her. When she wakes up, he tells her about Giasone’s betrayal. She orders him to have Giasone killed. Giasone struggles in the Labyrinth, as part of his quest for the Fleece; then he sails to Corinth, with Medea. A love affair develops between Oreste and Alinda, Isifile’s companion. Egeo learns of the lovers’ flight from Demo and decides to follow them. When their ship sinks, Demo believes that he is dead and in a whale’s stomach. Another love affair begins between Alinda and Besso. Oreste tells Giasone that Isifile is looking for him. Giasone tries to distance Medea, who wants to meet her rival, by explaining to her that she is a visionary. Isifile walks in on the romantic duo, interrupting them. To get rid of her, Giasone promises her his love, and he arranges for them to meet in an inn. He gives in to her request for a kiss, as a token of his honesty. Once again, a romantic duo is interrupted: it is Medea’s turn to walk in on Giasone and Isifile. To pacify her, Giasone asks her to meet him too, and promises that Besso will have Isifile killed. To Besso, Giasone demands that the first person to appear be thrown into the sea, no matter if they are man or woman.

Egeo, dressed up as a seaman, meets Demo who, still convinced to be dead, mistakes him for a spirit. Suspicious, Medea appears before Besso: captured by Giasone’ soldiers, she believes that her lover has betrayed her. When Isifile arrives, Besso sends her away. Thrown into the water, Medea is rescued by Egeo; she entrusts him with her revenge. Giasone, convinced that Besso carried out his mission, tries to fall asleep, and he dreams of the ghosts of the two women. Egeo tries to kill him, but Isifile prevents him from doing so. She is wrongly accused of the attempted murder, and Egeo runs away. While Besso announces Medea’s death, the latter appears and reveals the whole plot. Then, Egeo’s testimony clears up the situation. Isifile wants to kill herself out of romantic disappointment, but the depth of her feelings wins Giasone back. Everyone, including Medea, can now rejoice.