Butterfly Effect is the sixteenth episode of NCIS Season 20 and the 451st episode of the entire NCIS series.
Synopsis
When a potential biological terrorist attack occurs in the parking garage of a strip mall, NCIS investigate while Knight struggles as her father in Japan deals with a health scare.
Prologue
Act One
Act Two
Act Three
Act Four
Knight in the Evidence Garage.
Act Five
Cast
Series Regulars
| Name | Portrayed by | Role |
|---|---|---|
| Timothy McGee | Sean Murray | Senior Agent for the NCIS Major Case Response Team. |
| Nicholas Torres | Wilmer Valderrama | Special Agent for the NCIS Major Case Response Team. |
| James Palmer | Brian Dietzen | Chief Medical Examiner for the NCIS Major Case Response Team. |
| Kasie Hines | Diona Reasonover | NCIS Forensic Specialist. |
| Jessica Knight | Katrina Law | NCIS Special Agent. |
| Donald Mallard | David McCallum | NCIS Historian. Despite being credited, McCallum doesn't appear in this episode. |
| Leon Vance | Rocky Carroll | NCIS Director. |
| Alden Parker | Gary Cole | Special Agent in Charge of the NCIS Major Case Response Team. |
Other Cast
| Name | Portrayed by | Role |
|---|---|---|
| Dorothy Quinlan | Julianne Collins | Phillip Legrand's daughter. |
| Phillip Legrand | Greg Benson | Dorothy Quinlan's father. |
| Constance Miller | Brigid Brannagh | Senator. |
| Nate Billings | Sonny Valicenti | Spy. |
| Boggs | Tina Huang | Navy Captain. |
| Martinez (Butterfly Effect) | Al Rodrigo | MPD officer. |
| Sheehan | Johnny Jay Lee | Navy Petty Officer. |
| George Barlow | Dominic Pace | |
| William Jolson | Jimmy Walker Jr. | Former Sergeant. |
| Cole (Butterfly Effect) | Mircea Oprea | Metro Police Department Officer. Uncredited role. |