NCIS - Los Angeles Database
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Purity is the twentieth episode of NCIS: Los Angeles Season Four as well as the 92nd episode of the entire series.


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 as the search for the source of the cyanide.


Main Characters

Name Portrayed by Occupation
G. Callen Chris O'Donnell Special Agent-in-Charge, NCIS:OSP
Kensi Blye Daniela Ruah Special Agent, NCIS:OSP
Sam Hanna LL Cool J Special Agent, NCIS:OSP
Henrietta Lange Linda Hunt Operations Manager, NCIS:OSP
Eric Beale Barrett Foa Tech Operator NCIS: OSP
Marty Deeks Eric Christian Olsen LAPD Liaison to NCIS: OSP
Nell Jones Renée Felice Smith Intelligence Analyst, NCIS: OSP

Guest Characters

Name Portrayed by Notes
Roger Morgan Steve Tom
Lawrence De Vries Tom Gallop
Dominic Fryman Chris Bruno
Randall Baker Jay Ellis Flight Officer, U.S. Navy
Zaki Faheem Omar Elba
Alex Fryman Owen Teague
Ashley Hong Lily Mariye
Cam Steven W. Bailey
Lopez Mark Espinoza LAPD Detective
Crawford Travis Aaron Wade Chief Petty Officer, U.S. Navy
Eugene Rance Howard
Joshua Gordon Jade Carter Lieutenant, U.S. Navy
Alessandra Bree Condon
News Reporter Kent Shocknek
EMT Driver Oscar Magana Jr.

Detailed Summary

Major Events