Original Airdate: January 2, 2006
Writer(s): Damian Kindler
Director(s): Andy Mikita
Mitch Pileggi as Col. Steven Caldwell
Kavan Smith as Maj. Lorne
Chuck Campbell as Technician
Gerry Durand as Sergeant
Synopsis: Sheppard and Weir become a threat to Atlantis when their minds are taken over by hostile entities.