She is a supervillainess from the Radioactive Man universe, and the only female member of The Fossil Fuel Four. She is described by Radioactive Man as a "French Femme Fatale".
At the start of the episode Bart and Milhouse are reading the latest Radioactive Man comic; an animated sequence depicting what they are reading then plays out. Radioactive Man is flying through the skies when he discovers The Fossil Fuel Four attacking the Zenith City nuclear power plant. He tries to get backup from fellow heroes, Citizen Solar and Wind Lad, but Briquette tauntingly tells him that they are out of energy.
So Radioactive Man attempts to fight the villainous foursome on his own, but he is completely outmatched, with all four of the villains dishing out their own personal brand of punishment on the hero. After Radioactive Man has gasoline and coal fired at him, it is then Charcoal Briquette's turn to attack. Using her grill to set things on fire is the move she seems to enjoy using the most, and she does just that to the hero, causing him to run around yelping in pain as he burns. The Fracker then follows up with his attack on the still burning hero, which launches Radioactive Man up into space. He then falls back down to earth and crashes through a building.
Radioactive Man tries to get up, but the energy bars on his chest decrease from the combined punishment, and he collapses and dies. The Fracker picks up the corpse of the hero and raises it triumphantly, as Charcoal Briquette grins with delight at the sight of the deceased superhero, and at her involvement in his death.
The story then zooms out of the comic, revealing Bart's surprise at Radioactive Man being killed off.