An Ancient stone tablet, stolen by Vala and translated by Daniel, had been written by Myrddin (Merlin) and had described an incredible treasure buried at Glastonbury, also known as Avalon. Almost a half mile beneath Glastonbury Tor, SG-1 discovered a large main cavern, a network of tunnels, and some smaller caves, with no visible access from the surface and shielded by Ancient technology. Inside the cavern, a holographic image of Merlin stated that one must prove oneself worthy in order to attain access to "the storehouse of riches of Ambrosius Aurelianus." Scholars have speculated that Ambrosius Aurelianus and King Arthur may have been one and the same, although Ambrosius, the son of the Emperor Constantine, would have been 74 years old at the Battle of Mount Badon. Nevertheless, legends suggesting that the Knights of the Round Table had gathered great treasures from the far corners of Arthur's domain, possibly including the Holy Grail, and had hidden them in a magical stronghold at Avalon, also added weight to the theory that Merlin had protected King Arthur's treasure beneath Glastonbury. To prove themselves worthy, SG-1 had to pass three tests, including a riddle based on the proverb that the universe is infinite, a riddle related to the teachings of Buddhism to reflect on the eightfold path, and combat with the guardian of the treasure, a holographic knight.

When the tasks had been completed, a vast treasure suddenly and miraculously materialized in the cave. Merlin's treasure filled the cavern with extraordinary riches of gold and jewels. SG-1 also discovered several Ancient texts, including a book that told the story of the Alterans and confirmed for the first time that the Ancients had originally been a race that had come to Avalon from a distant galaxy, possibly leaving others of their race behind. Also among the gold and jewels was a piece of technology, an Ancient communication terminal, which enabled SG-1 to communicate with the home galaxy of the Alterans, where they made contact for the first time with the Ori. Merlin's treasure also included a phase-shift device of Merlin's design, known as Arthur's Mantle, which had been created to hide the secret of Merlin's weapon, a device that could destroy the Ori.

Cross Reference: Alterans, Ancients, Ancient Communication Terminal, Avalon, Glastonbury, Merlin, Merlin's Phase-Shift Device, Merlin's Tablet

Episode Reference: Avalon