Natasha Romanoff confronts the darker parts of her ledger when a dangerous conspiracy with ties to her past arises.
 
This is not your usual "run of the mill" Marvel superhero movie.  This one is more along the lines of an espionage adventure.  Almost like a James Bond film starring Roger Moore.  It's definitely worth watching, but it is a filler film in the MCU created for a post credit scene.
 
FUN FACT:  Yelena mistakenly calls Alexei "Crimson Dynamo" rather than Red Guardian. In the comics, Crimson Dynamo is a Russian supervillain in powerful armor who usually fights Iron Man, and has been a teammate of Red Guardian. His real name was Anton Vanko, and he is the father of Ivan Vanko (Mickey Rourke) from Iron Man 2 (2010), whose electricity-based weaponry and armor were based on the Crimson Dynamo from the comics.