Review: NCIS: Los Angeles Season 4, Episode 20 – "Purity" "Purity" is a high-stakes, technically intriguing episode of NCIS: Los Angeles that leans heavily into the team’s undercover capabilities. Originally aired on April 9, 2013, the episode centers on a domestic terrorism plot involving cyanide poisoning.
: G. Callen (Chris O'Donnell) infiltrates the group by staging a public brawl with Sam Hanna (LL Cool J). This leads to a tense sequence where Callen's cover is blown, and he is nearly killed by the very cyanide he's investigating, only saved by a timely counteragent. NCIS.Los.Angeles.S04E20.HDTV.x264-LOL.[VTV].mp4
: Kensi Blye (Daniela Ruah) and Marty Deeks (Eric Christian Olsen) provide the legwork, with Deeks notably diving into a dumpster to find a critical syringe. Review: NCIS: Los Angeles Season 4, Episode 20