Gibbs chooses to step away from the primary investigation to support a grieving Tobias Fornell, whose life is spiraling following his wife's murder.
The NCIS team investigates an explosion at a global terror summit, suspecting Gibbs' arch-nemesis, Sergei Mishnev. Episode 15: Cabin Fever
John Locke, Ben, and Hurley search for the mysterious "Jacob's cabin" to find answers about the Island's future. Gibbs chooses to step away from the primary
The episode concludes the long-running Mishnev storyline when Fornell kills him, finally avenging his wife. suspecting Gibbs' arch-nemesis
It introduces the idea that the Island must be "moved" and highlights the supernatural protection surrounding certain characters who "can't die" because their mission isn't over.