LL Cool J, Chris O'Donnell Photo

From: Photo Flash: NCIS: LOS ANGELES' 'Purity,' Airing 4/9

On NCIS: LOS ANGELES' upcoming episode, titled 'Purity,' when cyanide in a communal water jug lethally poisons a lieutenant and leaves a Navy pilot in serious condition, the NCIS: LA team investigates whether this is an isolated incident or an early test for large-scale water contamination, on Tuesday, April 9 (9:00-10:00 PM, ET/PT) on CBS.