When a Marine corporal dies in a tide pool after being exposed to fentanyl, the NCIS team must quickly find the source of the drugs; Alex talks to his parents about taking a gap year; Ernie reveals personal news to Lucy.
The SWAT team looks for an escaped convict who is planning to kill Tan and the law enforcement team who helped put him in prison several years ago. Then, Chris arrests a young man who is given a free pass.