Exhausted from trying to fix an epidemic of mechanical problems on the station Chief O'Brien becomes ill with a mysterious ailment that transforms speech into an incomprehensible babble. When Lt. Dax succumbs to the same ailment, tests reveal that both have been infected by the same virus. Soon the virus causes an epidemic of babbling on Deep Space Nine, and Commander Sisko is forced to put the entire station under quarantine. While searching for the source of the outbreak, Major Kira Nerys stumbles upon a Bajoran device planted some 18 years earlier. Now it's up to her to track down the virus' creator and find a cure before the epidemic turns deadly.

Matthew Faison (Dr. Surmak Ren)
Jack Kehler (Captain Jaheel)
Ann Gillespie (Nurse Jabara)
Richard Ryder (Bajoran Deputy)
Geraldine Farrell (Galis Blin)
Bo Zenga (Asoth)
Frank Novak (Businessman)
Kathleen Wirt (Aphasia Victim)
Lee Brooks (Aphasia Victim)
Todd Feder (Federation Male)

• The virus was activated by Chief O'Brien while fixing a command-level replicator. It then spread through the food served by Quark, and then mutated into an air-born virus.