Danny and Baez work with Texas Ranger Waylon Gates when they are put on a case to find the Lone Star Killer; after Eddie's partner mistakenly shoots an undercover cop, internal affairs accuses Jamie of not supervising properly.
When an informant is murdered, the team dig in to track down the perpetrator only to learn a shocking truth; Voight and Ruzek strategise to help Burgess.
Sherlock and Watson investigate a death of a wealthy businessman supposedly caused by a spectral animal.
Harper gets caught in a firefight when she, Abe and Maya travel to Syria to investigate a Marine accused of desertion; Colonel Turnbull travels to Germany to be with her wounded son.