After a man is shot multiple times and left for dead, and a kilo of diluted heroin is found in his car, Antonio discovers other similar cases where murder victims were found with the same type of adulterated drugs. Ultimately, the narcotics detectives involved in the case-one a decorated hero-appear to be the common thread. Meanwhile, Stone is hesitant to let Nagel be involved in the case, as she has a close connection to the victim.