Antonio, a rich merchant of Venice, is sad in mind but cannot tell why. Three of his friends meet him and make fun of his mood in the hope that it will disappear, but Antonio remains strangely unhappy. One of his friends, Bassanio, is closer to him than the others, and when these two are left together, Bassanio tells Antonio of his own concerns : he is a gentleman, but he has spent most of his fortune and now wants to go across the sea to woo a rich and beautiful girl called Portia. She has already given him some encouragement, but princely suitors are known to be on their way to woo her, and Bassanio has therefore to compete with them in display if he is to win Portia's hand in marriage. Antonio is very willing to lend him money for the journey, but his own fortune is not at the moment available; it is all in trading ships at sea. But he knows a Jewish money-lender in Venice, and persuades Bassanio to ask him for the money, with Antonio making himself responsible for seeing that the loan is paid back. The Jew, Shylock, has no liking for Antonio, because Antonio has often insulted him for being a Jew, and because the Christian has on occasion lent money freely whereas the Jew always charges interest, and has consequently lost business. However, Shylock agrees to lend Bassanio money, but on the condition, which he pretends is nothing but a joke, that if the loan is not paid back with a certain time, he will have the right to cut a pound of flesh from whatever part of Antonio's body he may choose. Antonio agrees, and Bassanio is able to set sail for Belmont Portia's house.
Portia, meanwhile, is being visited by other men wishing to marry her. They each have to submit to a kind of lottery, in accordance with the will of her dead father : they are shown three boxes, one made of gold, another of silver, and another of lead. One box contains Portia's portrait, and the suitor who chooses this one wins her in marriage. The Princes of Morocco and Arragon...