Jealousy is what made most of Iagos plans a success. Iago was the bad guy and Othello was the good guy, and everybody else that was affected didn't do anything to deserve it. Iago was the mastermind that planed everybody's painful death. Iago lies to Casio to try to make Othello kind of disbelieving in Desdemona and think that she is with Casio.
Othello gave his wife Desdemona a handkerchief that his dead mother gave to him. Then Iago planned to get that handkerchief and he did succeed, he got it from Emilia who falls for Iagos trick. Iago gave the handkerchief to Casio, then Othello sees the same handkerchief that he had gave to Desdemona. So now Othello is angry because he saw Casio with the handkerchief. After this Iago is allied with Othello and they plan to kill Casio and Desdemona.
Iago tells Othello to strangle his wife but Othello wants to poison her. Somehow Iago convinces Othello to strangle her and also promises Casio's death to Othello. That night Iago gets his puppet Rodrigo and tells him to go and kill Casio, and Rodrigo is so stupid and obeys Iagos commands. Rodrigo does not kill Casio but Iago does get a good shot at Casio's leg.
Since Rodrigo does not kill Casio, Iago goes ahead and kills Rodrigo and making Casio think that Iago is still his friend. Since Iago does not succeed in killing Casio, Iago starts to panic and thinks his plans are going to fail. But since Othello kill Desdemona, everyone races to their room and most of the characters in Othello are there. Othello confesses that he killed Desdemona, but because she was sleeping with Casio. Every one doubts him so Othello says that he saw Casio with the handkerchief he gave Desdemona. Then Emilia jumps in and is about to say something but Iago whispers something to her and tells her that its time to go home, but Emilia refuses and starts to speak out and says that the handkerchief was left behind in the bed and she picked it up.
She also says that Iago was the one with the handkerchief and he was the one that gave it to Casio to frame him. Iago goes and kills Emilia and tries to run away but he is caught. After this Othello is mad and Casio slips him a dagger and he stabs Iago and Iago says that he's not dead. Filled with anger Othello kills himself and a little later Iago goes and dies too in the bed filled with death..