It's Halloween and the NCIS team is busy investigating a ransom case. A Marine's daughter has been kidnapped after the kidnapper attacked a Marine in his home. The investigation leads them to a fact that the couple has been separated. They decide to focus on the wife's ex-boyfriend, after learning that the woman is the one who destroyed their marriage. Meanwhile, McGee and Tony are stunned by Abby's Halloween costume.

The team investigates the death of a petty officer and discovers he may have been leading a violent secret life.

The dismembered fingertips and teeth of a murdered Marine are discovered in the stolen purse of a pickpocketer, launching NCIS on a mission to find a cold-blooded killer.