S11, E7: Lt. Van Buren (S. Epatha Merkerson) is under pressure from the Chief to increase the precinct's conviction average, so she urges the detectives to look up old cases. They find an unsolved murder of a well-to-do teenage girl from 1981. Going back through files and talking to the detectives on the case, Tommy Callahan (Brad Sullivan) and Jimmy Cunan (James Hanlon) find that the prime suspect was a plumber who was in the house the day of the murder.