Gratiano and Salarino, masked and costumed for Bassanio's party, wait for Lorenzo under the overhanging roof (the "penthouse") of Shylock's house. Gratiano is puzzled that Lorenzo is late for his rendezvous with Jessica; he knows that lovers usually "run before the dock." Lorenzo's delay is certainly uncharacteristic of most young lovers.
Suddenly, Lorenzo rushes onstage, apologizes for his lateness, and calls to Jessica. She appears above, dressed as a boy, and tosses down a casket of money and jewels to Lorenzo. Shyly, she says that she is ashamed to be eloping with her beloved while she is so unbecomingly dressed as a boy. "Cupid himself," she tells Lorenzo, "would blush." Lorenzo tells her that she must play her part well; not only must she successfully be convincing as a boy, but she must also be his torchbearer at Bassanio's party — a fact that unnerves her. The idea of "hold[ing] a candle to [her] shames" is frightening. She is certain that what Lorenzo is asking of her will lead to discovery, and she feels that she "should be obscured." Lorenzo is finally able to reassure her, however, and Jessica turns back to do two last things before they elope. She wants to "make fast the doors" (as her father instructed her to do), and she wants to get "some more ducats."
Gratiano praises her, and Lorenzo reaffirms that he will love her in his "constant soul," for she is "wise, fair, and true." Jessica then enters below, and the lovers and Salarino exit.
Antonio enters and, finding Gratiano, tells him that there will be "no masque tonight." The wind has changed, and Bassanio and his men must sail for Belmont. Gratiano admits that he is relieved that there will be no feasting and no masque. He is anxious to be "under sail and gone tonight."
There is no real break between this scene and the preceding one. As Shylock exits, and Jessica exits only moments later, Gratiano and Salarino enter, costumed for the masque and carrying torches. Gratiano, as we might expect, does most of the talking as the two chaps wait beneath the overhanging roof of Shylock's house.
When Lorenzo arrives onstage and Jessica appears above him, a modern audience would almost certainly think of the lovers Romeo and Juliet. Thus the romantic mood is immediately set — except that this romantic heroine is dressed in "the lovely garnish of a boy." This was a popular and recurrent Elizabethan stage convention, and a very convenient one, since all the girls' roles were played by boys. Shakespeare uses this disguise convention later in this same play with Portia and Nerissa disguised as a lawyer and his clerk.
At this point, since Jessica is both deserting her father's house and robbing it, it is almost too easy, in one sense, to disapprove of her; Shylock hasn't really shown us a truly villainous side. One doesn't take the "pound of flesh" bond literally — yet.