Head of the Snake is the 5th episode of NCIS Season 18 and also the 403rd episode of the entire NCIS series.
Gibbs and Fornell's crusade to find the head of the drug ring responsible for Fornell's daughter Emily's overdose comes to a climax while Gibbs and Vance finally let the team in on a case that has dangerous implications.
- This episode airs on the same night as Sunburn (episode).
- This reveals that the reason Leroy Jethro Gibbs shoots Timothy McGee in Sturgeon Season (episode) was to save him as the plane he was approaching has a bomb inside.
|Leroy Jethro Gibbs||Mark Harmon||Special Agent in charge of the NCIS Major Case Response Team.|
|Timothy McGee||Sean Murray||Senior Special Agent and second-in command of the NCIS Major Case Response Team.|
|Eleanor Bishop||Emily Wickersham||Special Agent for the NCIS Major Case Response Team.|
|Nicholas Torres||Wilmer Valderrama||Special Agent for the NCIS Major Case Response Team.|
|Jacqueline Sloane||Maria Bello||NCIS Forensic Psychologist.|
|James Palmer||Brian Dietzen||Chief Medical Examiner for the Major Case Response Team.|
|Kasie Hines||Diona Reasonover||NCIS Forensic Specialist.|
|Leon Vance||Rocky Carroll||Director of NCIS|
|Donald Mallard||David McCallum||NCIS Historian. Despite being credited, McCallum doesn't appear in this episode.|
|Delilah Fielding||Margo Harshman||McGee's wife.|
|Merriweather a.k.a. Alexi Myshkin||Nick Boraine|
|Sasha Myshkin||Anna Grace Barlow||A.K.A. Karen. Merriweather's daughter.|
|Vladmir Ivanov||Isiah Adams||A.K.A. Chad Hamilton. Drug dealer and shifting manager at Beltway Burger.|
|Emily Fornell||Juliette Angelo||Fornell's daughter.|
|Tobias Fornell||Joe Spano|
|Samuel Miles||Tajh Bellow||Navy Petty Officer Second Class.|