Verdict: Action star Jolie rescues spy film from fatal attack of improbability, just.
Assessing the merits of Salt presents a difficulty. If you comment on its implausibilities, its contrivances, the vast leaps it makes in both its logic and in its many stunts ... well you've pretty much given away the entire film.
Then again, so does the trailer. In that we see a blonde Angelina Jolie being chased down on suspicion of being a Russian spy and a brunette Jolie under arrest, kicking and tasering her way out of a police car. In the film those points pretty much define the first act.
Far-fetched as it is, Salt is still robustly entertaining throughout. The recent arrest of a ring of Russian sleeper spies might have given its espionage plot, and its Cold War nostalgia, a boost in credibility.
But in a way those real-world headlines work against the mad conspiracy plot at the centre of this. Salt exists in a world where only the locations - Washington DC and New York with a few flashbacks to Mother Russia - are credible.
Everything else is designed to elicit: "Bloody hell, whatever next?"
And keeping you guessing about Jolie's character's next move is what this rollercoaster movie - and the star who plays her - do rather well.
Jolie is at the centre of everything in the film and seems to revel in the outlandish action heroics required of her, with every far-fetched escape - there must be half a dozen at least - from the authorities managing to out-do the previous one.
And she carries it off neatly even when she has to be disguised as a man under a couple of kilos of latex which reminds not so much of Mission: Impossible - Tom Cruise rejected starring in this because he thought it was too close to his franchise - but one of those Eddie Murphy multiple identity comedies.
As yet another superspy with a few personal demons, Jolie's believably bruising performance and her wiry energy save Salt from itself.
Sure, she's no Jason Bourne but she is in a film that is only really interested in getting to the next twist before we have a chance to fathom how ridiculous the last one was.
In that mission, it almost works.
Cast: Angelina Jolie, Liev Schreiber
Director: Phillip Noyce
Rating: M (violence and offensive language)
Running time: 100 mins