Bassanio asks for a loan of 3,000 ducats for 3 months and says Antonio will guarantee the loan.
$?
Shylock knows that Antonio owns a lot of ships.
Shylock will loan the money if he can talk to Antonio first.
?
Shylock dislikes Antonio for not charging interest and for being Christian. Shylock also confronts Antonio for insulting him previously.
Shylock says he will loan the money to Bassanio, but if the loan is not repaid per their agreement, then Shylock will take a pound of Antonio's flesh.
Pound of Flesh?
Shylock and Antonio agree to the terms of the loan, but Bassanio still doesn't trust Shylock.