It's Sin and Crossbones in Captain America #16
The Marvel Universe's version of Bonnie and Clyde are tearing their way through the country and unfortunately for Captain America, they happen to be two terrifying figures from his past.
The Red Skull is dead, but in Captain America #16, his daughter Sin has reappeared along with the Skull's longtime associate Crossbones and they're looking to kill and maim in the Skull's name.
Also, Captain America and Sharon Carter stumble across a secret AIM base with more shocking revelations for Cap, courtesy of writer Ed Brubaker alongside guest penciler Mike Perkins.
Drew Harmon of SilverBulletComics.com calls Brubaker's Captain America, "a definite must have. 5 out of 5." TheComicFanatic.com says, "Brubaker fires on all cylinders here, even managing to tug at the heartstrings of us old Cap fans. It's been ages since this title has been this good, and it has been even longer since I have looked forward to a new issue of Captain America. But with Brubaker at the helm, this book is THAT good and each new issue can't arrive quick enough."
Pick up Captain America #16 for the continuation of the new story arc that sets up just how deadly Sin and Crossbones can really be. After the conclusion of the Winter Soldier story arc, Cap had better hope he is on top of his game because Sin and Crossbones are not in the business of showing mercy.