This is almost like Mr and Mrs Smith Part 2, minus Mr Smith (although an inclusion of Brad Pitt is very much welcome). I don't think anyone else can carry out Salt role as perfect as Angelina Jolie. She is a nail on for the tough lady act.
So, the story is about an American agent said to be an agent for Russia, secretly brought in to bring down the good relationship between America and Russia. Salt denies that she is an undercover for Russia and has to go all out to prove her innocence and to save her husband.
Action-packed all the way.