Last issue, Crossbones restored Sin’s memory that she is really Red Skull’s daughter, and now they’re doing the “Natural Born Killers” thing. 

They rage across the Midwest, robbing banks and killing everyone in sight.

Sharon and Cap track them down and uncover an AIM plot that was also being investigated by Winter Soldier.  They’re told about a giant robot spider and a crazy person who fought it…

Sin and Crossbones are trying to destroy all evidence of the AIM project, after stealing the weapons the group was developing.

There’s a big battle, but Crossbones and Sin get away and capture a SHIELD agent, who they force to tell them that General Lukin killed Red Skull.

This continues to be an excellent spy/superhero amalgam.  One of the best long-form comic stories of all time.