: Callen’s cover is blown, and he is nearly killed by cyanide himself, only surviving by using a counteragent. The team eventually locates the group's base and prevents the mass poisoning. Technical File Details
: Indicates the file was distributed or indexed by the ETTV community. Cast & Credits G. Callen Chris O'Donnell Sam Hanna Kensi Blye Daniela Ruah Marty Deeks Eric Christian Olsen Hetty Lange Linda Hunt Director Eric Laneuville Writer NCIS: Los Angeles Season 4 Episode 20 Recap: Purity NCIS Los Angeles S04E20 HDTV x264-LOL[ettv]
: Callen goes undercover by attending a DNA rally, where he stages a fight with Sam to gain the group's trust. : Callen’s cover is blown, and he is