Nash and Joe trail two brothers who are heirs to a Mafia family. Nash becomes suspicious when he discovers Kelly once had a relationship with the younger brother.

Nash is stuck with an eleven year old delinquent who's the link to busting a drug kingpin. Joe is reunited with his grown son J.J. and Nick wreaks havoc with Nash's attempt to find him a live-in nurse.

A sniper terrorizes San Francisco on Halloween as a city-wide Blue Flu forces our SIU detectives to assume beat cop responsibilities. Joe tracks down a hard to find Halloween costume for Lucia.