Nicolle Galland's novel recasts Iago, not Othello, as the tragic hero and infuses him with much needed humanity.
Alas, Galland kept all the title names the same and in doing such; both rode on the coattails of Shakespeare's legacy - which, hypocritically, is why I bought this book - and subjected herself to comparison to him.
Iago's plan appears to succeed when Othello kills Desdemona, who is innocent of Iago's charges. At the beginning of the play, Iago claims to have been unfairly passed over for promotion to the rank of Othello's lieutenant in favour of Michael Cassio.
Iago is one of the most notorious and mysterious villains of all time—it's no accident that the hyper-annoying and malicious sidekick to Jafar in Disney's Aladdin was named Iago. At one point, Iago says he's angry because Othello passed him over for a promotion.
A while later, Othello's growing jealousy turns into anger and he threatens Iago with death and damnation if the charges against Desdemona cannot be proved. Bad move Iago's capacity for cruelty seems limitless, and no motivation he gives for his actions seems enough to explain the incredible destruction he wreaks on the lives of the people he knows best.
Mad with jealousy, Othello orders Iago to kill Cassio, promising to make him lieutenant in return. Are you a man?
O heaven forbid me! Of course Othello is absolutely wrong about honest Iago's motivations.