Photo Flash: First Look - CHICAGO FIRE's 'Fireworks,' Airing 3/20

On CHICAGO FIRE's upcoming episode, titled "Fireworks," with tensions still running high between Chief Boden (Eamonn Walker) and Bennie Severide (guest star Treat Williams), things boil over when Mills confronts Bennie about the fire that killed his father. Meanwhile, Severide (Taylor Kinney), Casey (Jesse Spencer) and Bennie uncover the truth behind two mysterious diner fires and Shay (Lauren German) takes a new direction with her plan to have a baby. Monica Raymund, Charlie Barnett and David Eigenberg also star. Chaon Cross guest stars. "Fireworks" airs March 20 at 10:00 p.m. on NBC.

Check out a first look below!

Photos by: ElizaBeth Morris/NBC

Jesse Spencer, Joe Minoso

Yuri Sardarov, Christian Stolte, Charlie Barnett, Joe Minoso, Taylor Kinney

Treat Williams

Charlie Barnett, Taylor Kinney, Yuri Sardarov

Jesse Spencer, Taylor Kinney

Eamonn Walker

Taylor Kinney

Joe Minoso, Jesse Spencer

Taylor Kinney