NCIS crosses paths with Whistler's team while investigating a shipping container filled with contraband weapons; Tennant debates arresting Alex's friend's dad, knowing it will cause her friend to move away.

Kai goes undercover as a chef in a local restaurant to gather intel on a notorious criminal kingpin who has a connection to the eatery. Also, Jane discovers that a school on the mainland has recruited Alex on a baseball scholarship, which he's kept secret from his family.

The NCIS team investigates a shipwreck carrying exotic animals that now threaten the native wildlife on Oahu. Also, Alex sustains a career-ending injury and Kai asks Melanie, a fish and wildlife agent, out on a date.

The NCIS team's investigation takes them deep into the world of illegal street racing after a Marine staff sergeant's body is discovered in a junkyard. Also, Tennant is concerned Alex is hiding something from her, and Whistler is anxious about introducing Lucy to her co-workers.

The NCIS team investigates the death of a Navy sailor and goes head-to-head with a ruthless local criminal organization. Also, Lucy looks for a new apartment.

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.

Captain Milius returns to Hawai’i as the NCIS team works to catch a dangerous high-value U.S. Government target with the help of an informant unlike any they’ve ever encountered. Also, Tennant and Daniel deal with Alex’s acceptance into the Naval Academy