Chicago Fire 4×19 “I Will Be Walking” – When a high school student becomes an innocent victim of a gang retribution incident, a very determined Lt. Casey (Jesse Spencer) tries all means necessary to resolve the issue. Severide (Taylor Kinney) lends a hand to Detective Holloway (guest star Jenny Mollen), who is working a dangerous undercover investigation, and watches over her 9-year-old son at the firehouse. Brett (Kara Killmer) and Jimmie (Steven R. McQueen) are called to aid a woman who takes a fond liking to Jimmy. Meanwhile, Otis (Yuri Sardarov) makes a surprising discovery that leaves him very concerned and Herrmann (David Eigenberg) goes toe-to-toe with Stella (guest star Miranda Rae Mayo) to claim bragging rights over who can best run a bar. Eamonn Walker, Monica Raymund, Joe Minoso and Christian Stolte also star. Jon Seda, LaRoyce Hawkins and Nick Gehlfuss also guest star.