When an ATF agent goes missing, the bureau seeks help from the NCIS team to investigate stolen military-grade weapons and locate the agent. Also, Callen and Anna continue to plan their wedding, Rountree's sister interviews for medical school and Sam encourages his father to take part in the drug trial.

"A Salute to 'NCIS: Los Angeles,'" an "Entertainment Tonight" special, will air after the series finale on Sunday, May 21. The one-hour special features footage and interviews with NCIS: LOS ANGELES cast members from the past 14 years, including current exclusive interviews, favorite memories and behind-the-scenes moments from the ENTERTAINMENT TONIGHT vault.