Warning! This article contains SPOILERS for Black Widow.
Avengers: Infinity War. Just like the other Avengers who also sided with Cap in Civil War, Natasha is a fugitive of the law for violating the Sokovia Accords and is on the run.
In Black Widow, Natasha discovers her attempts to end the Red Room by killing its leader, Dreykov, were futile. He survived and has continued his operation of taking young girls and turning then into more Black Widows. These new Widows are controlled with chemical conditioning that suppresses their will - a mind control Natasha's long-lost sister, Yelena Belova (Florence Pugh), only escapes thanks to an antidote. The similarities between the renewed Red Room and real instances of human trafficking, particularly of young women, are very apparent in Black Widow, and its director made sure the casting reflected this global issue.
In a chat with AV Club, Cate Shortland shared that she wanted to address how young girls across the world are subjected to immense abuse for someone’s gain. To do this, Shortland cast the Widows with a diverse group of actors from across the globes. The goal was to establish the far-reaching impact of the Red Room, the global scale at which they operated, and “to talk to all women.”
We cast our Widows from all across the world. So we had African widows, French widows, Norwegian widows, Korean, Chinese, British.
Black Widow starting with an array of mock found footage to establish that young girls from across the globe have been forcibly inducted into the Red Room doesn’t end up being a mere effect for the story. Even though the other Black Widows are only briefly seen throughout the film, their diversity lends authenticity to the overarching narrative. Hopefully, this was not the last outing for the Black Widows who were liberated from the Red Room and left with Yelena, Melina Vostokoff, and the Red Guardian at the end.
The post-credits scene in Black Widow features the return of Valentina from appearing alongside Yelena when she s the Disney+ series, Hawkeye,and presumably carries forward the mantle of Black Widow.
Source: AV Club