The Battle of Northbridge is the climactic conflict in Hero, Vol. 1. It was orchestrated as part of Silas Prescott's plan to take over the city with his army of super-powered criminals.
Prelude
Following the explosion at the Prescott Industries gala, Silas Prescott assigns Hazel to research the prism crystal to determine why only some of those present were granted superpowers. After Hazel experiments on the crystal, she manages to extract energy from it and creates a serum known as liquid prism, which Silas stores in a warehouse. He then hires a gang of thieves steal the serum from him so that he can distribute the serum to criminals and create an army of supervillains while he can officially deny his involvement for the moment. Silas also recruits Shrapnel and his henchmen to be his lackeys.
The Battle
Your Character and your team of superheroes engage Silas and his henchmen in a vicious brawl after Silas attacks the Mayor and destroys several buildings. You enlist Grayson's help in getting the civilians to safety and he apologizes for the harm his father has caused. You can tell him you're also sorry and Grayson, not recognizing you in your mask and disguise, is confused, but nonetheless takes charge of the evacuation efforts.
Throughout the battle, Dax and Poppy offer tactical advice via headset, with M.A.R.C.I. helping if you acquired the final suit upgrade. Minuet fights Shrapnel's henchmen, Talos fights Shrapnel, and you face off against Silas. Caleb assists your friends in fighting the super-powered henchmen if you recruited him previously. Your friends help you with your fight against Silas in turn, with Minuet slowing Silas so that your attacks can land and Talos shielding you from blasts of energy.
During the fight, Silas continues to inject himself with liquid prism until it becomes too much for his body to handle. You realize that this will eventually cause him to explode and kill everyone in a 100 mile radius, including your friends and all the people of Northbridge. You fly Silas into space to protect the city as your friends protest and beg you not to sacrifice yourself.
Aftermath
You ask Silas why he did what he did, and he explains that he was searching for a way to bring back his late wife in hopes that Grayson will "finally have a mother again." Silas explodes in a burst of prism energy, and his fate remains unclear at the end of Volume 1. You wake up in the prism dimension and comfort M.A.R.C.I. (if she is present), while the rest of Northbridge is left to believe you died saving the city.