This OGN brings back Red Guardian, Black Widow’s ex-husband and a reminder of her early appearances where she was cast as a villain. Red Guardian supposedly died in Avengers #44.
Only he didn’t.
He’s alive and has no memory of Widow. And the Russian Government is about to kill him because they can’t get him to remember his old life and he’s too much of a potential liability to be allowed to live. Widow goes down memory lane (to update readers who aren’t insane enough, like me, to have read every Marvel comic ever made), talks with some friends like Hawkeye and Daredevil, and then goes on a rescue mission.
The whole thing ends up being a trick. Guardian really is dead, and the Russian KGB was trying to trick Widow into stealing a chip from Nick Fury that would activate a Red Guardian life model decoy.
Threads from this story can be found in the MCU Black Widow solo movie.
Note: I tagged the original Red Guardian, even though he doesn’t appear, because he is in several flashbacks and is used as a lynchpin for this story.