Everything Starts Somewhere is the 2nd episode of NCIS Season 18 and also the 400th episode of the entire NCIS series.
Flashbacks reveal the murder case that first introduced young Gibbs to NCIS and his introduction to young, new-to-America Ducky.
- Gibbs had been revealed to have initially broken up with Shannon out of fear of losing love due to his job as a Marine at the very least risking him undergoing long deployments if not killing him, until Ducky, citing his breakup with Maggie Clarke, talked him out of it.
- Gibbs ended up abducted while heading to a wedding by Vito Zucado in 1980, and had met Ducky after the latter accidentally saved him by crashing into Vito's car due to unfamiliarity with driving customs in America.
- It was revealed that Gibbs' house had formerly belonged to Ducky.
- Gibbs had missed out on every anniversary regarding McGee's becoming an NCIS agent, with it being implied that it coincided with Shannon's death.
- It's revealed or implied that the Anniversary of McGee becoming an NCIS Agent occurs the week after Gibbs' Wedding Anniversary to his first wife Shannon.
- Mark Harmon's son Sean returns to portray the younger version of his father's character. He last appeared in the 14th episode of season 9, Life Before His Eyes.
|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.|
|Young Ducky||Adam Campbell||Younger version of Ducky Mallard|
|Young Gibbs||Sean Harmon||Younger version of Agent Leroy Jethro Gibbs|
|Jonny Zucado||Vito D’Ambrosio|
|Doctor Walter Magnus||Thomas Crawford||NIS Medical Examiner|
|Edward Scott||Dajuan Johnson||NIS Special Agent|
|Michelle Stamos||Gabrielle Walsh||NIS Special Agent|
|Young Jonny Zucado||Matthew Furfaro|
|Emilio “Freckles” Zucado||Louis Mustillo|
|Young Freckles||Jered Solow|
|Young Franks||Ben Turner Dixon|