The NCIS team investigate a car explosion in Washington D.C. that leaves a Navy Commander dead, his Marine wife unconscious and their teenage daughter unharmed but shocked with the team soon digging deeper and discovering that there's a connection to an NCIS Special Agent who went missing six months ago while on a deep undercover assignment in Argentina and as the case goes on, NCIS Special Agent Alexandra Quinn, an instructor at FLETC arrives at NCIS HQ and begins shadowing the team in order to find out why Gibbs rejected the eight agents she recommended.
- It's revealed that since DiNozzo's resignation and McGee's subsequent promotion to Senior Field Agent, three months ago, there have been at least eight possible replacements for McGee's former position, all trained by Alexandra Quinn but none have lasted due to Gibbs firing them.
- Fornell is revealed to be living at Gibbs's house as he recovers from the injuries he sustained in Homefront (episode).
- Bud Roberts Jr. returns and it's revealed that he has been promoted to Captain.
- McGee is revealed to know Bud and Bud's JAG colleagues, Captain Harmon Rabb and Marine Colonel Sarah MacKenzie.
- NCIS Special Agents Nicholas Torres and Alexandra Quinn are both introduced for the first time.
- After the case has been solved, Torres and Quinn both join Gibbs's team on a permanent basis.
|Leroy Jethro Gibbs||Mark Harmon||Special Agent in charge of the NCIS Major Case Response Team.|
|Abigail Sciuto||Pauley Perrette||Chief Forensic Specialist for the NCIS Major Case Response Team.|
|Timothy McGee||Sean Murray||Senior Special Agent and second-in command of the NCIS Major Case Response Team.|
|Nicholas Torres||Wilmer Valderrama||NCIS Special Agent who has recently returned to D.C. after disappearing while undercover six months ago.|
|Alexandra Quinn||Jennifer Esposito||NCIS Special Agent and a trainer at FLETC.|
|Eleanor Bishop||Emily Wickersham||Probationary Agent for the NCIS Major Case Response Team.|
|James Palmer||Brian Dietzen||Assistant Medical Examiner for the NCIS Major Case Response Team.|
|Leon Vance||Rocky Carroll||Director of NCIS.|
|Donald Mallard||David McCallum||Chief Medical Examiner for the NCIS Major Case Response Team.|
|Tobias Fornell||Joe Spano||FBI Special Agent recovering from injuries he sustained in the last season.|
|Bud Roberts Jr.||Patrick Labyorteaux||A lawyer with JAG and also a Captain in the United States Navy.|
|Elena Silva||Sol Rodriguez||Leo Silva's daughter and David Silva's sister.|
|Leo Silva||Juan Carlos Cantu||South American businessman and also a hidden crime boss.|
|David Silva||Nicholas Gonzalez||Leo Silva's son and Elena Silva's brother.|
|George Campbell||Shaw Jones||A Commander in the United States Navy.|
|Amanda Campbell||Ciara Bravo||Daughter of George and Lucia Campbell and the niece of NCIS Special Agent Nicholas Torres.|
|Monica Fernandez||Gina Gallego||A Judge.|
|Terry Mahler||Brian Michael Jones||Probationary Agent with NCIS.|
|Lucia Campbell||Pilar Holland||A Marine with JAG and sister of NCIS Special Agent Nicholas Torres.|
|Franco Alvarez||Bayardo De Murguia||A man who appears in the episode.|
|Suited Man||Joshua Elijah Reese||A man who appears in the episode.|
|Waitress (Rogue)||Samantha Cutaran||A woman who appears in the episode.|