Code of Conduct

On Halloween night the team investigates what looks to be the unfortunate suicide of Lance Corporal James Korby who is found dead in his car. However, they soon discover that Korby was murdered as his organs were frozen with liquid nitrogen and that when he attempted to breathe, the nitrogen entered his lungs, suffocating him. However it's also discovered that Korby has scar-tissue from a previous poisoning and Gibbs suspect that the entire squad, fed up of Korby's jokes attempted to kill him. Someone got Korby to drink the nitrogen and staged his death to look it like a suicide. Tony can't shake the hunch that Sara, Korby's wife and a three-time marine widower, is involved, suspecting her of being a Black Widow. It's soon revealed that Private Singer, who belonged to Korby's unit, was having an affair with Korby's wife Sara. Sara also confesses to coming home to confront Korby right around the time of the crime but getting cold feet at the last second. Just as Tony is about to cuff Sara for Korby's murder, Gibbs realizes that Sara had nothing to do with Korby's death because there was someone else with a real motive: Rachel, Korby and Sara's teenage stepdaughter. Having been about to cash in on a pretty hefty trust fund and inheritance, Rachel knew the only way she could do it was by murdering Korby and then framing Sara for his death. ­In the meantime, Ziva attempts to come to terms with her new role as an NCIS Special Agent and the Probie of the team as Tony begins referring to her as Probie, something she begs him not to do for her sanity but Tony continues to do it anyway. Later, in true Halloween style, Ziva gets her own back on Tony by pretending to bow down to him and as a gift gives him a cup of coffee but when Tony drinks it and smiles at her, it's shown that his teeth have turned blue.