In the first part of a crossover with "Chicago P.D.," a spate of robberies comes to light after a firehouse lockbox key goes missing. CPD's Voight has suspicions that a firefighter may be involved, and with Boden's support he recruits Cruz to go undercover and help sniff out any suspicious activity.
Elenco: Jesse Spencer , Taylor Kinney , David Eigenberg , Joe Minoso , Christian Stolte , Eamonn Walker , Yuriy Sardarov , Kara Killmer , Monica Raymund , Miranda Rae Mayo , Charlie Barnett , Lauren German , Annie Ilonzeh , Alberto Rosende , Dora Madison , Steven R. McQueen , Daniel Kyri , Hanako Greensmith .