As of June 2019, no plot has been announced. Sonja's backstory in the Marvel Comics is a grim one as it established her as a 17-year-old woman living in the fictional Western Hyrkanian steppes with her father, mother, and two brothers. Sonja is turned into "the She-Devil with the Sword" after a group of mercenaries kill her family, physically assault her, and take all of the family's possessions. A broken young woman, the red goddess Scathach endowed Sonja with the incredible skill to handle any weapons, especially swords, under the special provision she would never be with a man unless he defeated her in fair combat.
In 2009, this reboot of the original film was announced. Robert Rodriguez was announced to direct and Rose McGowan was announced to star as Red Sonja, succeeding Brigitte Nielsen in the role. But due to Conan the Barbarian (2011) bombing at the Box Office, production on the reboot was abandoned and both Robert Rodriguez and Rose McGowan backed out of the project. As of 2015, the reboot is in development hell but left development hell in August 2022 with MJ as the director
Two promotional posters for the movie were released during the Comic Con in 2008. Both featured Rose McGowan, dressed as Red Sonja with fierce red hair. On one she was licking blood from a sword and on the other she was kneeling on a pile of skulls with red plots flying around her. Both posters promoted the movie to be released in 2009. It was never released that year.
As of June 2019 the project has been reported as "back in track" after Jill Soloway was signed on to write and direct. Since then, Solloway chose to be referred to as non-binary and now goes by the name Joey.
Based on the fierce 6-foot tall female warrior character Red Sonja, who first appeared in Marvel's Conan the Barbarian comics back in 1972, Red Sonja soon became a popular enough character to warrant getting her own Marvel run. Dynamite Entertainment helped revive interest in the Red Sonja franchise in 2005 and continues to publish new stories about the She-Devil with the Sword.