Arthur's Mantle

Plot:

Sam manages to activate an Ancient device they found at the Glastonbury site and she and Mitchell are shifted into a phase that makes them invisible to everyone. Daniel soon figures out just what is going on but Dr. Lee's proposed solution sends Daniel to the same plane as Sam and Mitchell. There he is able to translate information explaining that Merlin had created a weapon against the Ori - and provides a gate address where it can be found. Meanwhile, Teal'c travels to a Jaffa planet that has sent out a distress call. The two events are related.