Tristen MacDonald

After an ambush changes the course of the their investigation, the NCIS team has to quickly find answers, and one team member flashes back to their very first NCIS assignment.

A patient's desire to end her life triggers haunting memories for Hunt; Arizona and Callie have different opinions about the future; Richard tries to adjust to his new role.

On the night of a young man's 21st birthday, his friends take him out to celebrate, but when they turn up dead and he's found walking in the middle of the street covered in his friends' blood and wielding an axe, the CSIs must trace the events of the man's wild night to figure out just what happened. (TV-14)

An attack on a graduate student developing a weapon for the Navy is tied to international warfare.

Callen must interrogate his father after he is found in a patient's hospital room during a case.

Callen goes undercover at a hospital to find an NSA agent who vanished while tracking an ISIS cell.