Continuing from the previous episode, Bridgit Pike decides to kill her brothers after being abused, going into a vigilante crusade, forcing Gordon to stop her with the help from Selina Kyle.
Meanwhile, the strike force, led by Gordon, catch a thug and accuse him of being the arsonist who killed Officer Garrett in the previous episode.
Bridgit is brought back to the Pike home, where her brothers taunt her fear of fire by threatening her with firecrackers.
In an underground facility of a division of Wayne Enterprises, Bridgit, still alive, is brought to Indian Hill labs where scientists experiment on human beings.
The episode received a rating of 79% with an average score of 6.5 out of 10 on the review aggregator Rotten Tomatoes, with the site's consensus stating: "Though season two continues to struggle with tonal consistency, 'By Fire' sets up a fun showdown between some of Gotham's most explosive characters.
"[3] Matt Fowler of IGN gave the episode a "good" 7.4 out of 10 and wrote in his verdict: "'By Fire' may have been another one of this show's villain-as-a-kid origin tales, but it was utilized nicely right at the end to open up a whole new side of the series - that of the Indian Hill monster farm.
Club's Kyle Fowle gave the episode a "C" grade and wrote, "The biggest problem plaguing 'By Fire,' and really Gotham as a whole, is that it wants to explore the story of Gordon’s potentially compromised morality with as much gravitas as possible while also insisting that the more comic and cartoonish tendencies are fine because hey, this is just a comic book show, right?
It’s a flippancy that’s insulting to anyone who watches the show and tries to invest in these characters, and it’s a general lack of attention paid to storytelling that results in frustrating swings in tone.