Sandra prosecutes a drug company that's ""using inner-city babies as lab rats"" to test a measles vaccine; officials unearth the identity of the man who killed Michael's family; Gaffney pursues a relationship with a bond trader; and Oliver learns his father has cancer.

Tony Garufi, the man who had Mike's family murdered, is killed the week before he's scheduled to get a subpoena. Meanwhile, after charges of statutory rape against a popular ballet dancer are dropped in L.A., Sandra decides to prosecute him on a Federal level; and Oliver initiates a case against a tobacco company.

Michael resents having to help an attorney prosecute a man involved in the murder of his family - a case he wanted to handle - so he withholds information; and Oliver is arrested after the tobacco company plants cocaine in his car.

Erica assigns Jessica to prosecute an artist who took nude photos of her friend's daughter and posted them on the Internet; and Michael resumes work on the mob case, but is frustrated when agents discover there's a leak among them.

Mrs. Abruzzi gives Michael a tip leading to Iredesco's arrest after learning that her husband's killer also murdered Michael's family; a tobacco-company informant dies after warning Oliver and Jessica of a secret agency that monitors the anti-smoking movement.