Chicago Fire

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: LaRoyce Hawkins as Officer Kevin Atwater -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Jesse Spencer as Matthew Casey -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Jesse Spencer as Matthew Casey -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Jesse Spencer as Matthew Casey -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Marina Squerciati as Officer Kim Burgess -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Dylan Baker as Arata -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) Eamonn Walker as Chief Wallace Boden, Joe Minoso as Joe Cruz, Charlie Barnett as Peter Mills -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) Jon Seda as Antonio Dawson, Jason Beghe as Hank Voight, Sophia Bush as Erin Lindsay -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Sophia Bush as Erin Lindsay -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) David Eigenberg as Christopher Herrmann, Charlie Barnett as Peter Mills -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) David Eigenberg as Christopher Herrmann, Christian Stolte as Mouch -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) Christian Stolte as Mouch, David Eigenberg as Christopher Herrmann -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: Christian Stolte as Mouch -- (Photo by: Elizabeth Morris/NBC)

CHICAGO FIRE -- "A Dark Day" Episode 218 -- Pictured: (l-r) David Eigenberg as Christopher Herrmann, Yuri Sardarov as Brian "Otis" Zvonecek, Joe Minoso as Joe Cruz, Christian Stolte as Mouch, Charlie Barnett as Peter Mills -- (Photo by: Elizabeth Morris/NBC)