From the log in Merlin's phase-shift device, SG-1 learned that Merlin had developed a weapon capable of destroying ascended beings, but he had hidden his work from the Others by shifting his research into another dimension. SG-1 sought Merlin's weapon as their best hope to defeat the Ori, and they began their quest by following the gate address indicated in Merlin's log, an address which brought them to Camelot on PX1-767.

In Camelot, SG-1 was greeted by Meurik, the governor, and Antonius, the village historian, who informed them that King Arthur and his fellow knights had set off long ago to find the Sangreal, and one day he will return to them. Sangreal refers to the Holy Grail, but the notion that the Grail was a cup or chalice, particularly the one used by Christ at the Last Supper, was a late addition to the myth. Earlier accounts describe it variously as a dish or platter, or, in the case of Von Eschenbach and other Middle Eastern influenced chroniclers, as a stone that fell from the heavens. Sangreal, from the Latin "sang," meaning "blood," is also known as the bloodstone, a jewel blood-red in color. Although SG-1 searched Merlin's library thoroughly, they were unable to find anything resembling a Sangreal. It was Meruik who identified the Sangreal as the blood-red stone in the pendant that Merlin wore, but Arthur and his knights had left to quest for the Sangreal long ago. According to Merlin's prophecy, they had journeyed to three distant lands - Castiana, Sahal, and Vagon Brei. SG-1 continued their search on Vagon Brei, a world that had been decimated by illness. In Atlantis, Daniel learned from Morgan Le Fay that the Ancient names of Castiana and Sahal were Taoth Vaclarush and Valos Cor, however a search of these two worlds again turned up no sign of the Sangreal.

Adria and Ba'al were also searching for Merlin's weapon, and Adria sent a dream to Vala that the address of the planet they sought was a combination of "three into one." Daniel had noticed that the coordinates of Castiana, Sahal, and Vagon Brei formed an equilateral triangle and that the addition of Camelot as a departure point formed a perfect tetrahedron. A search of planetary designations made up of a combination of symbols from the three addresses produced only one result, and SG-1 visited the new planet only to find that both Adria and Ba'al had preceded them there. Circumstances demanded that they cooperate in their quest, and together they negotiated the safeguards that Morgan Le Fay had put in place to ensure that the Sangreal could only be claimed by those possessing truth of spirit. The Parchment of Virtues in the village archive provided the key to solving a time distortion maze, a force field trap, a crying child, a series of riddles, a wall of fire, and a fire breathing dragon.

Within the cave beneath the lone mountain, SG-1 found a holographic image of the blood-red stone, the Sangreal, on a pedestal before an obelisk. When Daniel attempted to grasp the image, the obelisk activated, and SG-1 and Ba'al were sent to Merlin's cave on another world, however the device had not permitted Adria to pass, and she was left behind. In the cave they found Merlin in stasis. When he had awakened and revived, Merlin interfaced with an Ancient repository device to design and configure virtual holographic components from base molecules. As each component was completed, it materialized into solid form, and the Sangreal, the red jewel, was to be the final component, the key to making his weapon work.

Merlin was too weakened to finish the weapon himself, but by uploading his knowledge into the repository device, he enabled Daniel to complete the task. When Daniel was made a Prior by Adria, he had constructed most of the components of the weapon, and he devised a plan that would enable SG-1 to finish the weapon and send it to the Ori galaxy. Using Daniel's directions, Vala completed the final components and added the Sangreal stone, which was held suspended above the device and glowed when it was ready to be activated with the timing crystal. The Sangreal completed Merlin's weapon, and the device was armed and sent on an Ori warship through the supergate to the Ori galaxy, however there was no way to determine if the weapon had successfully destroyed the Ori.

Cross Reference: Adria, Ancient Repository, Ba'al, Camelot, Castiana, Crystals, Force Field Trap, Merlin, Merlin's Cave, Merlin's Library, Merlin's Weapon, Meurik, Morgan Le Fay, Ori, PX1-767, Parchment of Virtues, Sahal, Sangreal Dragon, Sangreal Planet, Taoth Vaclarush, Time Distortion Maze, Vagon Brei, Valos Cor

Episode Reference: Camelot, The Quest, The Shroud