It deals with the climax of the "Dark Reign" storyline, which saw the character Norman Osborn become the United States primary defense officer, leading H.A.M.M.E.R.

The story depicts Loki manipulating Osborn into leading an all-out assault on Asgard, at the time located within a fictional United States.

The "Siege" storyline consists of an eponymous four-issue mini-series, and a number of related tie-in books, including one-shots, miniseries, and existing ongoing series.

This five-part series focused on Thor, Iron Man, and Captain America and bridged the gap between "Siege" and "Heroic Age".

On Loki's advice, Osborn engineers a tragedy in which the hapless Asgardian Volstagg, manipulated into battling the super-villain team the U-Foes, accidentally causes an explosion that kills everyone in a crowded Soldier Field football stadium in Chicago, Illinois.

The siege begins with the Sentry attacking Asgard, followed by a massive aerial assault led by Osborn in his Iron Patriot armor.

At the same time, the Avengers resistance led by Tigra, Justice, and Gauntlet launch their own attack on Camp H.A.M.M.E.R., aimed at eliminating Osborn's Initiative.

Osborn's people offer Todd Keller, a conservative talk show host, exclusive official coverage of the siege, in order to mold public opinion.

Meanwhile, longtime investigative journalist Ben Urich, editor of the New York City newspaper The Front Line, heads to the Oklahoma battle site with cameraman Will Stern.

The siege continues with the super-villain Scourge using the enchanted spear of Asgard's ruler, Odin, to sever the left limbs of the superhero U.S.

[7] The conflicted hero Night Thrasher who had been compelled to make a Faustian bargain with Osborn, turns on him by battling his Cabal minion the Hood.

[8] In Washington, the President orders the Secretary of State to dispatch military forces to Oklahoma to have Osborn and the Dark Avengers arrested for treason.

Before anyone can react further, Osborn's armor, now under the control of its original inventor, Tony Stark explodes off his body on live television, revealing his face painted in the image of the Green Goblin.

[9] As the Void battles the Avengers, Loki repents and begs Odin to let him use the mystical Norn Stones to give the heroes the strength to win the day.

[15] Rogers says that he will continue the 50 State Initiative and reform the original Avengers group with Bucky (as Captain America), Stark, and Thor as its main members.