Captain Ross is murdered while working undercover with the Feds to bring down an arms dealer. Detective Nichols then joins Goren and Eames to find his killer, but the Feds don't want him to compromise their investigation.
Nichols and Stevens discover that the murder of a magazine editor could be related to the Russian mob, but later uncover evidence of a relationship between the victim and the daughter of the editor who replaced him.
A Health and Human Resources employee trying to shake down the owners of a hospital dies under suspicious circumstances, and the investigation leads to a notorious mobster's son, who is trying to become a legitimate businessman.
Nichols investigates the death of an old family friend, which may be related to a fabled manuscript that dates back to the time of Christ. But his investigation is complicated by his past relationship with the victim's daughter.