Black Widow: the least Avenger-like movie in the series

f you're going to have a Russian-engineered chemical sprayed in your face, it might as well be a sparkly red substance that lands like fairy dust. That glittery, enigmatic scene in Black Widow is only one of the fresh choices in the film about Natasha Romanoff, trained as a Russian assassin before she joined the good guys and turned Avenger. The movie seemed to take forever to arrive, with scripts and rumours gestating for years, then a 14-month-long pandemic delay. The time lapse turned out to be an asset. Tensions between Russia and the West have ramped up more than anyone might have guessed in 2010 when the Avengers franchise brought in Scarlett Johansson as Black Widow in Iron Man 2. Now her movie lands at just the right time, sending Natasha back to Russia, a country that continues to be one of Hollywood's great villains.

Maybe it's no surprise that the film is entertaining and full of action. It is unexpected, though, that Black Widow may be the least Avenger-like movie in the series so far. No offence to the other Avengers, but after all this time a tweak in the formula is a good thing. Black Widow sets itself apart by emphasising Natasha's past, and her reunion with her fractured, drolly comic family. Not a peep out of those other superheroes.

A swift, exciting 10-minute opening fills in the background. In an Ohio suburb in 1995, 12-year-old Natasha, her hair dyed blue, lives with her blonde little sister, Yelena, and their parents, Alexei and Melina. Played by Rachel Weisz and David Harbour, the parents are like the Jennings in the spy series The Americans, Russian agents hiding in plain sight.

Cate Shortland, who has directed small character-driven films (including the eloquent World War Two drama Lore) might seemed like an unusual choice for Black Widow, but she quickly demonstrates that she can create exhilarating action. When the family has to make a quick escape from the US, Dad shoots at oncoming police cars, Mom pilots a getaway plane, and even Natasha is called on as co-pilot as they leave the only true home the girls have ever known. The sisters, who are not actually related to each other or the bogus parents, are sent to the Red Room, where Russia trains girls to be spies and assassins.

Florence Pugh makes Yelena, now a Russian assassin, the most vibrant person in the film

The film then leaps ahead 21 years. If anyone is keeping track (and there's really no need to) that places the story chronologically after Captain America: Civil War, with the band broken up. It comes before Avengers: Endgame, in which Natasha gives up her life to save the world because that's just what Avengers do – and why not, because does a good Avenger ever really stay dead?

We already knew that the Red Room was a part of Natasha's past. We didn't know about the sister, and she is a find. Florence Pugh makes Yelena, now a Russian assassin, the most vibrant person in the film, more lived-in than most action-movie characters. She is cynical, with a touch of mordant humour that masks how deeply bruised she was by the family abandonment. It is Yelena who encounters the glittering red chemical. It isn't giving too much away to say that the Russians have developed a synthetic formula that can suppress free will, the perfect metaphor for Russia v the West. There is nothing deep or heavy about the film's treatment of that idea, which simply floats in the air.

That chemical leads to Natasha and Yelena's reunion after years without any contact. At first they fight, kicking and throwing each other against the wall in Yelena's Budapest apartment, where Natasha once lived. (No need to fret about this if you didn't already care, but in some heavy-handed exposition, Natasha fills in a mystery, mentioned in earlier movies, about what happened in Budapest years before.)

Then the sisters team up to try to destroy the Red Room. They are bitter about how Russia moulded them into killers. The action is sleek, well-paced and more Mission: Impossible than Avengers. After all, they have no superhuman powers – no telekinesis or shape-shifting for them. They scramble across rooftops, race a motorcycle through gridlocked traffic, leap from planes and escape exploding cars.

Their self-imposed mission takes them back to Russia, where they track down Alexei and Melina. It's not Johansson's fault, and it doesn't particularly hurt the film, but Natasha is the least interesting character in that weird little fake family. The script gives the others better lines and weirder trajectories. Yelena makes fun of her famous sister for the way she always flicks her hair and assumes a "fighting pose" when taking on villains. She's not wrong. Alexei, a superfighter known as Red Guardian, is full of braggadocio and spins tall tales about having defeated Captain America. Harbour makes him a likeable doofus Dad. "For a couple of deep undercover agents I think we did pretty great as parents," he says. Natasha's sternness is a sign of her moral centre. And she's Black Widow; at this point in the franchise she doesn't need to win the audience over. But at times her earnestness is an odd fit for the sly family movie unfolding around her.

Black Widow does become typically Avengers at the end, with an overwrought, too-long action scene that plays like a festival of stunt doubles tossing each other around a Russian lab. The real ending is better: a post-credit sequence brings back Pugh as Yelena in a tease that is not terribly surprising but is extremely welcome.