The death of an American seaman on a U.S. nuclear submarine during an AUKUS ceremony on Sydney Harbour is investigated in a joint effort between America's NCIS agents afloat and the Australian Federal Police.

When a Navy compliance officer is found dead in a waterhole from a snakebite, the team works to uncover the origin of the rare deadly taipan that is uncommon to the area where the officer was discovered.

When a shark spits out an arm wearing U.S. Navy equipment, the team's investigation tests the loyalty of a band of former Navy divers.

When a U.S. petty officer's body is found in Sydney's historic and haunted Rocks area, a decades-old Navy Cross medal holds the clue to solving the murder, leading the team on a wild ghost chase to catch a killer.

The team races to save one of their own when Doc Roy and his dog are involved in a hostage situation at their local dog cafe.

When the suspicious death of an old Drug Squad colleague pulls Evie back into a secret undercover operation, DeShawn is torn between loyalty to his friend and loyalty to his team.

A glitzy tech launch turns into a disaster, leaving half of NCIS: Sydney trapped underground, and the others scrambling to save the day before the clock and the oxygen runs out.

When JD's son is kidnapped by an international assassin in exchange for a wanted criminal in NCIS custody, the team frantically tries to get his son back safely without trading in a criminal.

NCIS: Sydney will do whatever it takes to crack the case of a rogue assassin on the run during NCIS Special Agent DeShawn Jackson's chaotic first day as boss.

When a young girl finds the body of a former U.S. Navy officer floating in the harbor, the team is led to an 18th-century sailing ship hosting a pirate-themed wedding, where DeShawn and Evie go undercover to investigate. Meanwhile, Mackey and JD are pulled in to prevent a potential tragedy on the harbor that could rip the U.S.-Australia alliance apart.

When the body of a long-missing U.S. Naval engineer is discovered buried in concrete, the team enlists Doc Roy's old friend to assist in the investigation.

The team is thrown into the murky world of online conspiracies after a car owned by a U.S. Navy cyber engineer explodes just as her teenage daughter was about to take a driving lesson.