Ep 4. Doppelganger

The episode "Doppelganger" is the fourth episode of the fourth season of Stargate Atlantis. The episode begins with the Atlantis team discovering an abandoned Wraith hive ship. They enter the ship and find a strange room with a large crystal in the center. Rodney touches the crystal and suddenly has a vivid dream in which he is being chased by a demon-like creature.

The team returns to Atlantis, but soon realizes that something is not right. Rodney begins experiencing strange phenomena, such as seeing the demon creature in reality and feeling physical pain as a result of his dream. He also becomes very irritable and volatile, lashing out at his friends and colleagues.

The Atlantis team investigates and discovers that the crystal has the power to create doppelgangers - evil versions of a person's psyche that manifest when the crystal is activated. The doppelganger has all the knowledge and memories of its counterpart, but with an added sinister twist.

Rodney's doppelganger is wreaking havoc on Atlantis, causing all sorts of mayhem. It is up to the real Rodney and his team to find a way to stop the doppelganger before it destroys everything they hold dear.

As the episode progresses, tensions rise and the stakes get higher. It becomes clear that the doppelganger is not only a physical threat, but a psychological one as well. The characters are forced to confront their inner demons and face their fears if they are to survive.

The episode is full of suspense and drama, with a healthy dose of sci-fi elements that Stargate is known for. The special effects are top-notch, with the demon-like creature and the doppelganger both being well-designed and convincingly menacing.

Overall, "Doppelganger" is a thrilling episode that will keep viewers on the edge of their seats. It is a standout episode in an already great series, and is sure to please fans of both Stargate Atlantis and sci-fi in general.