The NCIS team suspects Gibbs' arch-nemesis is behind an explosion at a summit for global terror event, but Gibbs elects to sit out the investigation in order to help a grief-stricken Fornell, whose life is on the verge of imploding following his wife's murder.

Evidence in an NCIS murder case reveals a rare painting on loan had been swapped for a fake, prompting DiNozzo, Sr. to share his knowledge and contacts of the black market art world with the team.