Hide and Seek

Eager to experiment with new technology, Dr. McKay volunteers to be Dr. Beckett's first patient for his new ATA gene therapy. Now able to use a personal shield emitter, McKay recklessly tests its properties, only to find that it could lead to his death. Elsewhere, a "living shadow" entity threatens the city after it was accidentally released from a container where the Ancients were studying it. It roams the city looking for energy to feed on, and the more it feeds, the more lethal it becomes. Finally Atlantis expedition manage to send it to planet M4X-337.