Coroner Griscom (Austin Pendleton) alerts the homicide unit to the fact that several recent deaths have been caused by a poison named phospozine. FBI agent Mike "McGee" Giardello (Giancarlo Esposito) is put in charge of investigating this possible act of terrorism, whereupon tension develops between McGee and his father, Al (Yaphet Kotto), while Gharty (Peter Gerety) quietly and methodically traces the source of the poison. Meanwhile, Ballard (Callie Thorne) is none too pleased that the entire unit knows that she has dated Falsone (Jon Seda). And why is Munch (Richard Belzer) seeing a doctor? ~ Hal Erickson, Rovi