Set during the 'Secret Empire' event, Natasha Romanova was first seen after Cap'n Hyrda's reveal plotting a way to assassinate him. The Champions, a group of young heroes including the likes of Amadeus Cho's Hulk and Mile Morales' Spider-Man, found her and asked her to train them.
She agreed, starting up her own 'Red Room' (which was Russia's attempt at creating a super soldier) and began training the Champions with a brutal, no nonsense training regime. This wasn't the biggest issue though, as Morales was concerned about a vision that the Inhuman Ulysses had spoken of. It was one that showed the young Spider-Man killing Steve Rodgers.
When push came to shove and the team went to take down Cap'n Hyrda, Morales did engage in a fist fight with the dastardly despot, though Romanova had a plan to prevent him from becoming a murderer. She attempted to snipe the Cap'n yet was intercepted by a Hydra agent so she couldn't take the shot.
She did go to aid Morales in the fight, but Cap'n Hyrda did something that truly secured his position as the ‘least likeable prick in comics’. He cracked through Romanova's neck with his shield, killing her instantly. The death of Black Widow pushed Morales to the point where he could give the Aryan antagonist a royal beat-down, but the damage was done.
She's yet to come back in the comics, though Bucky Barnes did go on a search for her after hearing she may not be dead after all.