NCIS is charged with apprehending dangerous and elusive criminals that pose a threat to the nation's security. In a city that keeps surviving disaster, one elite team is dedicated to making its shores a little safer.    During the famous Mardi Gras parade, a young Naval oceanographer plunges to his death from a hotel balcony. It's up to Pride and his crew to investigate. But this is a case that goes from grisly to utterly strange. A gris-gris bag found in the victim's belongings, a trail of mystical clues, and the haunting figure of a voodoo loa on CCTV at the crime scene all suggest that dark powers are at work in The Big Easy.