After a convicted felon swears the NCIS agency framed him for murder a decade ago, Gibbs begins his own investigation, starting with a new autopsy by Ducky. Also, Senior FBI Agent Fornell joins the team, since he was the lead investigator in the original joint FBI and NCIS case.

The team's Thanksgiving plans are put on hold while they track an elusive international arms dealer in D.C. who recently murdered an MI-5 officer who was Sloane's close friend. Also, Abby races Delilah to the hospital when her labor starts three weeks early.