Stargate Atlantis: Season 1, Episode 16

1 - 16: The Brotherhood

The Atlantis team travels to Dagan, a planet with a hidden ZPM and a mysterious trail that will lead to its hidden secret chamber location. But the Genii have learned of the Atlantis team's activities on Dagan. Realizing the ZPM must hold awesome power, the Genii plant a sleeper agent amongst the Daganians aiding the Atlantis team on their search. Now, as the Atlantis team closes in on the location of the ZPM, the Genii close in on them.