Novak tries to find Benson when the case for a previous rape victim, Chelsea Arndale, hinges on her testimony. Benson, meanwhile, is still living as Persephone James and has been arrested in Oregon after the ecologist's group she has infiltrated is involved in a fracas with the local police. After the local sheriff advises her that her group is being looked at in connection with a recent murder, Benson decides to do a little investigating on her own and learns that the man was a pedophile. When she finally finds his private hideaway, it leads to a shocking conclusion.
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 is assigned to stop of shipment of smuggled diamonds and Bob is conflicted when he sees one of the men helping themselves to the diamonds. On the home front, Molly and Kim are raising money to help the men and women serving in Iraq. Tiffy debates the war with protesters from a local school.