Crossing the Line (S03E05)

After the murder of another Black police officer, the team fears he has fallen prey to the elusive killer cop. They interview Sgt. Durrant, who was present during a stop-and-search with the victim shortly before his demise, along with the individual who was searched. The detectives begin to believe that the crimes are racially charged and strive to protect a prominent target. Meanwhile, David and Vivienne push boundaries in their investigation.