“SWAK” - #045 - When a letter sealed with a kiss gets into the NCIS offices, two members of the team are quarantined for exposure to a biological agent on NCIS Tuesday, May 10, 2005 (8:00-9:00 PM, ET/PT) on CBS.  Dennis Smith directed the episode written by Executive Producer Donald P. Bellisario.

When a mysterious letter sealed with a kiss makes its way into the NCIS headquarters, Leroy Gibbs immediately locks down the building and the NCIS team is forced to carry out their biological attack protocol.

Abby gets right to work trying to figure out exactly what the substance is and learns that it is a genetically altered version of the plague.  Gibbs quickly starts the investigation to find out who sent the letter.  He knows that it is a race against time to find the sender and the antibody before this plague critically affects one of their own.