: Lieutenant Casey faces extreme pressure to cover for a drunk driver who paralyzed a teenager—only to discover the driver is the son of Detective Hank Voight.
: Characterized as a "dirty cop" from the start, Voight uses threats and intimidation to protect his son, Justin. [S1E3] Professional Courtesy
If you'd like to dive deeper into the Chicago franchise, I can provide: on the Casey vs. Voight rivalry resolution Character arcs for Severide or Mills in Season 1 Viewing order for One Chicago crossover events : Lieutenant Casey faces extreme pressure to cover
: Casey refuses to be intimidated by Voight , officially filing the report and setting off a multi-episode rivalry that defined the show's first season. [S1E3] Professional Courtesy
"Chicago Fire" Professional Courtesy (TV Episode 2012) - IMDb