Margaret 'Peggy' Carter is selected by Dr. Erskine to receive the first test sample of his super serum, after a number of more promising applicants are killed by a HYDRA explosive. The serum works but rather than risk Carter's life (and having a woman fighting on the front lines) Carter is pushed into the USO. She later becomes involved in commando work after a tour stop in France is hit by HYDRA saboteurs. She will eventually go on to fight Nazi wonder weapons, and prevent HYDRA from detonating a tesseract fueled weapon over North America. The war ends shortly after, but Miss America (ironic and annoying as Carter is British) is among those lost and presumed dead. (frozen in the ice)
Elizabeth 'Betty' Ross is working with her fiance Bruce Banner when there is an accident in the gamma ray thing, and she saves the lives of many people in the installation by manually overriding the system, subjecting herself to gamma ray saturation. She becomes a rampaging monster and tears a large portion of the lab apart. The story evolves as Dr. Banner chases after Ross, trying to help her control her new found powers and searching for a cure, while Ross's father blames Banner for his daughter's death and doesn't know the monster he is chasing is his daughter. Hijinks and smashing ensue.
As events in Asgard unfold, the power struggle between Thor, Loki, and Odin threatens to tear the Immortal Realm apart. To prevent a civil war, Brunnhilde, leader of the Valkyrior steals Mjolnier, Gungnir, and the Casket and escapes with them to Earth to hide them. Frost giants, Sif and the Warriors Three, and the Destroyer are dispatched to Earth by various groups to recover the various items of power and to kill or capture Brunnhilde. The Valkyrie uses Gungnir to great effect, SHIELD claims Mjolnier, and the Casket is mysteriously lost. Brunnhilde's final act of defiance is to destroy the Bifrost before it is used to destroy Earth, Jotunheim, or even is turned against Asgard itself.
After a disastrous PR campaign in Talibanistan, Tony Stark is left a neurotic PTSD mess. Unable to continue as Iron Man, his personal assistant Pepper Potts dons the armor and goes to work as Rescue. She is occassionally backed up by War Machine, and sometimes a very reluctant Tony in Iron Man. Rescue defeats Ironmonger and Stane's attempt to assassinate Tony, and herself before setting himself up as a lord of war.
The New Avengers assemble
The war in Asgard is going to spill over out of the Immortal Realm and threatens to draw Earth into the ongoing battles.
Seeking to draw the war out into three fronts Loki is planning on reigniting the fighting on Earth and is going to send mercenaries and frost giants to Earth to find the Casket, and possibly the other missing weapons. Brunnhilde comes out of hiding to once again protect the relics in SHIELD's care. Seeing the coming storm, Nichole Fury brings Rescue, Miss America (recently thawed) and She-Hulk together to form a counterstrike team. Brunnhilde is accepted into the team along with Jason Borne II/Robin Hood and Spider-Man (male version of the Black Widow).
Loki attends Earth personally, seeking specifically Gungnir and the Casket, and hoping to ensure that Mjolnier remains missing. Rescue with other Stark armor special forces fight the Chitauri mercenaries, while She-Hulk and the rest fight Frost Giants and Loki. Miss America shows up wielding Mjolnier and much ass is kicked in the Battle for New York.