In 2009, the Simurgh attacks Madison, Wisconsin; in addition to necessitating the quarantine of the city, by drawing on the technology of Professor Haywire, she brings a building containing a gaming team that would eventually become the Travelers from Earth Aleph into Earth Bet. In their attempts to sustain themselves, the Travelers acquire powers by drinking from Cauldron vials, but their main priority soon becomes helping Noelle, whose lower body begins to grow increasingly monstrous after drinking only half of a vial. Eventually, the Travelers are hired by Coil, who promises to find a cure for her, and they begin to claim territory in Brockton Bay.
The Travelers remain in Coil's employment as his plans develop, with Noelle placed in confinement in his base. The kidnapping of Dinah Alcott had long been a point of contention between Coil and his other employees, the Undersiders; as his plans come to fruition, Coil betrays the Undersiders, almost killing Skitter. Skitter survives the trap set for her, however, and eventually kills him. In his final act of spite, however, Coil releases Noelle, now focused on getting revenge upon the Undersiders, from her vault.
Noelle's absence is soon noticed as the Undersiders return to Coil's base. Ballistic explains the nature of her powers to them before they leave and encounter Miss Militia at a damaged building, who informs them that Vista has been kidnapped. They negotiate with the PRT, who keep Noelle as an A-Class threat despite Tattletale's efforts to persuade them. However, they do agree to work with the Undersiders (though with the potential threat of a kill order on them if things go wrong) and bring in Eidolon, Chevalier, Myrddin, and other Protectorate capes and Wards. After a brief strategy meeting and communication with Noelle herself, the capes move out and begin to act.
The battle had two stages, the first when the situation was considered A-Class.
Brockton Bay Wards were dedicated to stopping a scapes from attacking Vista's family. Hero teams were tasked with cleaning up clones.
Trickster joining Echidna helped push the undersiders and the Travalers off the board.
After being trapped in the remains of Coil's base, the heroes were given a brief respite before Echidna returned, augmented by the mass from Bitch's dogs. Here the Threat was upgraded into a S-Class and other assets were called in.
Myrddin was killed, along with several other capes in the belly of Echidna and ensuing fight.
Eidolon's clone had effectively discredited the Triumvirate, revealing their association with, as well as the very existence of, Cauldron. Contessa continued to silence people who were present at this event and spoke out about this for some time afterward. Case 53s broke away from the Protectorate as a result of this revelation, forming their own group, the Irregulars, while suspicion grew within the Protectorate itself about the loyalties of Cauldron capes. Heroes such as Pretender and Legend resigned from their positions, the latter being replaced by Chevalier as leader of the Protectorate. This damage persisted for years.