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Norman Osborn calls a meeting of the Cabal (Doctor Doom, The Hood, and Loki) to discuss Asgard, the last hold out in Osborn's consolidation of power. Namor and Emma Frost are absent due to their betrayal during the events of Utopia, and are replaced with Taskmaster. During the meeting Doom expresses his displeasure with Norman's actions against his ally Namor. Doom accuses Osborn of attempting to kill off members of the group that are not obedient to him, and orders Osborn to bring forth Namor. Upon refusal to do so Osborn has Doom attacked by an unknown assailant. After the attack Osborn examines the body to see that it is not Doom, but a small swarm of robotic insects inside a Doombot. The insects attack the Cabal and under the suggestion of Loki the Hood flees. Avengers Tower is ordered to be evacuated, with only Osborn staying to attempt to fight off the swarm. When his shields (as the Iron Patriot) are about to fail, Sentry comes in to destroy them.
Later, during a meeting with President Obama, Osborn tries to secure permissions to invade Asgard under the claim it poses a threat to national security. The President does not feel the threat is serious enough to warrant an invasion and orders Osborn to stand down. Loki, listening to the conversation, reminds Osborn of the superhuman Civil War, explaining that it all started with a tragedy in Stamford, Connecticut and that a similar tragedy could be used to gain approval for an assault.
Victoria Hand suggests to Norman to see a psychiatrist when she gets concerned about his Green Goblin side resurfacing. Soon the sky suddenly turns an unearthly color, heralding the return of Sentry; surrounded by the mysterious black Void tendrils seen in the previous issue. The tendrils start to damage New York City, wrecking buildings and causing havoc. While the Dark Avengers work on crowd control Norman talks down Void/Sentry, telling him that this kind of destructive behavior will gain the attention of powerful members of the 616, enough perhaps that it may make them realize they have to deal with Sentry once and for all. Sentry powers down, but Norman realizes that Sentry's wife Lindy Reynolds may have caused his recent meltdown. Realizing he has to deal with this problem, the episode ends with Osborne sending Hawkeye to kill Lindy. Bullseye takes her for a helicopter ride, and strangles her and dumps her body in the ocean. When the Sentry questions him about Lindy's whereabouts, Bullseye claims she committed suicide over the countryside by jumping out of the helicopter, and the Sentry flies off to find her.
The Soldier Field Tragedy
Asgardian hero Volstagg leaves the city of Asgard in order to have adventures on Earth, while Osborn and Loki see an opportunity to create the disaster they had discussed before. Volstagg reaches Chicago where he intervenes in a robbery, managing to stop the robbers but causing collateral damage as he is not used to having to balance out his strength among humans. He is then assaulted by the U-Foes, energy based villains at the bidding of Osborn by way of the Hood. Their fight leads them to Soldier Field, during a sold out football game. Vector and X-Ray bombard Volstagg with energy blasts, but while he manages to deflect their attacks, the blast's shockwave destroys and kills everyone in the stadium, causing the deaths of thousands of people and leaving the horrified Volstagg essentially unharmed.
Osborn and Loki watch this in astral forms, declaring that Asgard will now be held responsible for the disaster and approval of his military attack on the city is inevitable.
Norman Osborn returns to his office, where the attack has reached the news networks. Victoria Hand comes in to the room, where Osborn tells her to tell the President that they have everything in Chicago under control. He also tells her to assemble the Dark Avengers and the members of the Initiative loyal to him, declaring that they are invading Asgard. Later, Osborn is seen trying to convince Ares to come up with a plan to invade Asgard, even though Osborn promises Ares that nothing is wrong, Ares tells him that if he is lying, he will kill him. Then Osborn discusses with the rest of the Avengers about the plan. While they are worried about the plan, Osborn offers them the deal that if the invasion is successful, they don't have to work for him anymore. Ares gives a rousing speech for the Initiative, Avengers, and the entire H.A.M.M.E.R. team.
Meanwhile the President, unable to reach Osborn directly is unable to prevent the H.A.M.M.E.R. attack on Asgard, realizing that Osborn is beyond the government's control. Loki appears before Balder, warning him that Midgard is moving against Asgard.
The Siege of Asgard begins with the Sentry attacking Asgard, followed by a massive aerial assault led by Osborn himself.
Osborn leads the assault on Asgard
While this happens, Donald Blake says that Tony Stark's brain waves are still weak but are getting stronger everyday. He, along with Maria Hill, see the attack commence. Blake tells Hill to take Tony away from there as fast as possible. Blake then goes outside and transforms into Thor and heads directly towards Osborn, but gets attacked by the Sentry into the ground. Thor then strikes the Sentry, sending him flying away, but the combined blast from Osborn and several Initiative agents manage to hurt Thor, with Osborn managing to knock him out with one final blow. The Siege is being covered on the news, declaring that Thor has been brought down. All of this being watched by a furious Steve Rogers.
Todd Keller, a conservative talk show host, is approached by a H.A.M.M.E.R. agent on behalf of Norman Osborn to exclusively cover the invasion of Asgard. Meanwhile Ben Urich is arrested in Chicago for attempting to enter Soldier Field, blacklisted by Osborn. Will Stern, a cameraman spots Urich and convinces the arresting officer to release Urich into his custody. Urich and Stern then leave for a local diner where they have a chance encounter with Volstagg who is headed back to Asgard to turn himself into the Asgardian authorities. Urich and Stern realize that Osborn is attempting to shift public opinion by stacking the media in his favor. They then convince Volstagg to allow them to accompany him on his way back to Asgard to get his interview and to cover the invasion from another perspective.
During the battle Daken turns on Osborn, attacking and appearing to kill him. However it is revealed to him that Osborn is alive and unaware of his apparent treachery, the experience simply a hallucination brought on by the mysterious Asgardian figures the Norns.
Diamondback sees the Dark Avengers engaging Thor. Feeling the need to help him but feeling unable to herself she decides the only solution is to bring in the actual Avengers.
Hood reveals the Norn Stones to his crime syndicate and states that it can empower them with the ability to find the New Avengers and those responsible for helping Luke Cage escape. Living Laser assists some H.A.M.M.E.R. Agents into attack Bucky and Steve Rogers and is joined by Corruptor who corrupts Bucky. Captain America manages to knock Corruptor out. Mandrill and Griffin attack Spider-Man and Spider-Woman where Mandrill takes control of Spider-Woman.
The Death of a God
As the battle in Asgard intensifies, Ares finds himself battling Balder and learns from Heimdall about Osborn's deceptions. Meanwhile outside, Norman Osborn tells a battered and injured Thor that he is under arrest and that Asgard is now under his jurisdiction. Before he can take Thor into custody, Norman Osborn is attacked with a rocket launcher by Maria Hill and a young man named Jason. After fending off Moonstone and X-Ray of the U-Foes, they help get Thor to safety. In Brooklyn, Steve Rogers delivers a speech to the assembled members of the New Avengers and Young Avengers and well as the Secret Warriors and tells them that they're going to take back their country. Back in Asgard as Osborn dispatches Daken to find Maria Hill, he is struck down by Ares, who vows to kill Osborn for his lies. But Ares is suddenly attacked by the Sentry and a brutal battle ensues. It then comes to a violent conclusion when the Sentry literally tears Ares in half before the horrified eyes of the combatants on both sides.
Siege Vol 1 2 page 24-25
Sentry kills Ares.
Back in Brooklyn as the Avengers and Secret Warriors prepare to depart for Broxton, Bucky gives Steve back his shield. At first Steve refuses, but Bucky tells him that if he wants to take the country back from Osborn, he needs to put on his uniform and stand up. Edwin Jarvis then gives Steve a briefcase and asks him to give it to an unknown person (presumably Tony Stark) and asks him to help him.
Ben Urich, Will Stern and Volstagg reach a roadblock as they approach Broxton, Oklahoma and are spotted in their news van by H.A.M.M.E.R. agents. Volstagg exits the van and enganges the agents directly while Ben and Will speed off but are caught only moments later. While in custody at Tinker Air Force Base, Will fakes a seizure and knocks the unsuspecting guard unconscious when he comes to investigate. The two then take the guard's keys, free themselves and escape.
The Asgardians get word that Volstagg has turned himself in to the authorities. Knut warns the other Asgardians of a prophecy he just envisioned, but is dismissed. Loki tells Knut that he believes him and escorts Knut to his bedroom where Loki kills Knut. In the Broxton jail, Volstagg is speaking to the sheriff and his deputy as the news reports on the attack on Asgard, showing footage of Thor being beaten down. Realizing that what's going on is wrong, the sheriff releases Volstagg so that he can go help defend his home. Volstagg stops though, when he realizes all the lies that are being spread about him and the other Asgardians. The sheriff sets him up in front of a webcam, and Volstagg sends out a video to the world about what really happened in Chicago. Word quickly spreads, and people everywhere are beginning to question Norman Osborn and H.A.M.M.E.R.'s attack on Asgard. As Volstagg is leaving the police station, Thor lands in front of him and smacks him to the ground. Volstagg realizes that this is not the true Thor, this is Ragnarok.
Ultron is shown to infiltrate Jocasta and the Infinite Avengers Mansion. He names himself Ultron Pym and seeks to kill and replace his father before using his Infinite Mansion to conquer the universe.
Norman Osborn sends his Thunderbolts to infiltrate Asgard and steal a weapon from the Asgardian armory that will turn the tide in his favor.
When visiting his brother's grave, Donyell is conflicted if he should go with the deal Norman Osborn and the Hood gave him. Counter Force takes the fight to Camp H.A.M.M.E.R. and ends up fighting the Hood's gang. They are knocked down by Hood's new Asgardian weaponry. When Donyell arrives, Hood gives him an opportunity to prove himself by killing Tigra.
Spider-Man manages to free Spider-Woman from Mandrill's control and they managed to defeat Mandrill and Griffin. Meanwhile, Luke Cage assists Steve Rogers and Captain America in fighting off Living Laser. Nick Fury and his Secret Warriors arrive and fend off the H.A.M.M.E.R. Agents. Upon seeing Norman Osborn's attack on Asgard, Steve Rogers has the Avengers assemble to fight the Dark Avengers and those that are on Norman Osborn's side.
Nick Fury tries to restrain a furious Phobos, grieving the sudden loss of his estranged father. Back in Broxton as Osborn declares martial law in order to flush out Thor and Maria Hill, Daken is blasted by a bolt of lighting and severely burned. Thor then declares that he will not hide from Osborn or his minions and will defend both Broxton and Asgard with his last breath. Osborn orders the Sentry to find and kill Thor, but then receives a message from Taskmaster telling him to turn around. As Osborn does, the reflection of Captain America's shield can be seen coming closer can be seen in his faceplate.
Steve Rogers returns.
Meanwhile in Washington, the President is watching the invasion of Asgard with his security council and orders the Secretary of State to mobilize all available military forces to be dispatched to Broxton and to have Osborn and the Dark Avengers arrested for treason. He also says that they should all pray for a miracle, to which one of the counsel members remarks that he thinks they just got one because Captain America has just arrived and brought his friends with him.
Osborn is struck down by Captain America's shield as he and his allies descend onto the battlefield. As the Avengers, Young Avengers and Secret Warriors come to the aid of the Asgardians, Balder notices their arrival and welcomes their help. At the same time, Thor and Maria Hill are confronted by the Sentry. Thor unleashes a massive lightning blast against him, but it has little effect. As the Avengers advance through Asgard, they are met by the Hood, Madame Masque and all the members of his gang who attempt to bar their way. Elsewhere, Hill returns to Tony Stark's hiding place to move him to a safer location when Speed arrives with the briefcase Jarvis gave Captain America earlier. Hill orders Speed to surrender when Stark stops her and asks Speed to give him the case. Back in Washington, the President receives word that ground and air military units have arrived in Broxton and are awaiting his orders. The President decides to let Captain America and his allies deal with Osborn and his forces and to have the military units take down H.A.M.M.E.R. itself instead and they begin by opening fire on their Helicarrier, which sustains massive damage. Victoria Hand then gives the order for all hands to abandon ship. As Thor and the Sentry continue their battle, Captain American and Osborn face off against each other. As he strikes Ms. Marvel down with an energy blast, his Iron Patriot armor is completely shut down by the arrival of Stark (who is dressed in a variant of his MK III armor).
Enraged, Osborn orders the Sentry to annihilate Asgard rather than allow the Avengers to have it, which the Sentry does, practically leveling the city before the horrified eyes of Thor. Captain America finds Osborn amid the wreckage, pulls him out and places him under arrest. Before anyone can react further, Osborn's armor literally explodes off his body, revealing his face, which is painted in the image of the Green Goblin.
Osborn's madness revealed
This is witnessed across the country on live television by the entire nation with the X-Men and the Fantastic Four among those watching. Osborn begins raving that the heroes don't know what they've done, only to be punched out by Spider-Man. Thor demands to know the whereabouts of Loki, but Osborn tells him none of that matters and that he was the only one who could save them from what is about to happen. Osborn points overhead and hovering above them all is the Sentry, now fully possessed by the Void.
The weapon that the Thunderbolts stole from the Asgardian armory was actually Odin's spear. They ran afoul of The Mighty Avengers where Scourge ends up using Odin's spear to sever U.S. Agent's left limbs.
With the Void full possessing the Sentry, the creature starts making short work of Captain America's Avengers, the Young Avengers and the Secret Warriors. Filled with regret over what he had allowed to transpire, Loki, praying to Odin for help, summons the Norn Stones away from the Hood and uses them to empower the three hero teams, they begin fighting back against the Void. However, the beast realizes Loki's hand in this and attacks Loki, ripping him apart.
The death of Loki.
Before he dies, he begs Thor to avenge him. Enraged, Thor goes on the offensive, pummeling the Void with all his might. Getting an idea, Tony tells Thor to move the Void away from Asgard. Doing so, Tony commandeers the H.A.M.M.E.R. Helicarrier and crashes it into the Void. The resulting attack reverts the Sentry back to normal Robert Reynolds. In horror, Robert begs Thor to kill him. Thor refuses, declaring that he was going to make Robert pay for his crimes in prison. However, the Void begins to reappear and Thor is forced to gather his full strength and vanquish him. Thor, then, wraps him in his cape and sends him into the sun.
In the aftermath of the Siege of Asgard, the Hood and Madame Masque escaped the wreckage and began a race against time to reach Masque's father, Count Nefaria. Norman Osborn attempts to escape during the crashing of the Helicarrier, but is stop by Volstagg and Steve Rogers. When he's returned with the other villains, Moonstar attempts to escape as well, only to be stopped by Tony Stark after Captain America and Ms. Marvel fails to do so. However, Daken does escape custody. When Captain America asks Steve what he was going to do next, it is revealed that he is called to the White House for a conversation with the President. There, the President wants him to take over as head of security. However, Steve gives him one condition and that's that he does his way.
Steve Rogers meets with Barack Obama
This leads to the removal of the Superhuman Registration Act. 
At the same time, the New Avengers race after the Hood and Madame Masque, facing the two and Nefaria. With the help of Wolverine, the three villains are taken down before Luke receives a call from Jessica Jones over the repelling of the SRA. A number of heroes are gathered at Stark Tower, now reclaimed by Stark, when Thor and a number of Asgardians appear before them. Making one of Asgard's remaining towers appear on Stark Tower in place of the Watchtower, Thor declares Earth and Asgard as allies.