Photo Flash: CHICAGO FIRE's 'Viral'

On CHICAGO FIRE's upcoming episode, titled "Viral," the anguish that haunts Cruz (Joe Minoso) over his previous actions boils over, as he puts himself and his fellow firefighters in jeopardy. Casey (Jesse Spencer) and his sister Christie (guest star Nicole Forester) try to solve their issues with their mother (guest star Kathleen Quinlan) and each other. Meanwhile, Severide (Taylor Kinney) reaches out again to an important person from his past as a favor to Lieutenant Whaley (guest star Shane McRae) and the squad gains new perspective after assisting the bomb squad on an extremely dangerous call. Charlie Barnett, Monica Raymund, Lauren German, David Eigenberg and Eamonn Walker also star. Shiri Appleby also guest stars. "Viral" premieres February 20 at 10PM on NBC.

Check out a first look below!

Photo by: Matt Dinerstein/NBC

hane McRae, Eamonn Walker, Taylor Kinney, Jesse Spencer

Eamonn Walker, Taylor Kinney, Jesse Spencer

Monica Raymund, Lauren German

Taylor Kinney

Shane McRae

Taylor Kinney

Kelli Barrett, Taylor Kinney

Jesse Spencer

Monica Raymund, Lauren German

Shane McRae

Eamonn Walker