When Sheppard's team encounter a culture with phase shift technology that keeps their entire population invisible - and immaterial - to the outside world, it looks like Atlantis might have found the perfect protection from the Wraith. Eager to make a trade for the technology, Doctor Weir embarks on a diplomatic mission to negotiate with the people of Lannavulin. But once there, it becomes apparent that not everyone is happy with the planet's status quo...