As a major storm pounds Washington, a woman named Jacqueline Sloane bangs on Gibbs's door, claiming her car broke down. He invites her in for coffee but is soon called to a crime scene. He leaves her his keys and tells her to lock up when she's done there.
A Marine, Lt. Wynn, was attacked at a Halloween theme party and seriously injured by stab wounds. He survives, however, but he reports that the man who stabbed him also kidnapped his wife Helen.
Helen, a Navy officer stationed on a ship, also happened to be an heiress to a large fortune, and her mother is willing to pay any ransom. Only no ransom comes.
Torres and Bishop visit Helen's ship and discover that the ship's XO, Buckner, used to bully Bishop in high school.
The team learns that Helen and her husband had marital issues, to the point where she had drawn up divorce papers. Two weeks earlier, however, they'd decided to get back together.
Unfortunately, Helen turns up dead in the trunk of her car. From the clues left behind, however, the team concludes that the kidnapper didn't intend to kill her.
They discover that a petty officer planned to use her key to the Disbursement Office on the ship to steal the payroll. His onshore partner had killed Helen after she dumped him to get back with her husband.
Sloane reveals herself to be an NCIS agent and forensic psychologist. Later, however, Gibbs reveals that he had already figured out her identity from pretty much the start.