In the season 1 finale of NCIS - Unità anticrimine (Episode 23, titled "" or " Doppia identità "), the "useful paper" refers to the intelligence documents and photos that Ari Haswari used to manipulate the NCIS team and lead them into a trap.
The team uses communication "papers" and digital trails to track Ari after he wounded Ducky’s assistant, Gerald, in the previous episode. NCIS - UnitГ anticrimine 1x23
This episode originally aired on May 25, 2004, and serves as the conclusion to the Ari Haswari introduction arc. You can find more details about the episode's plot and cast on Movieplayer.it or IMDb . In the season 1 finale of NCIS -