Plot

Based on the information Vala gave them, SG-1 travels to the planet where Merlin may have hidden his secret weapon to defeat ascended beings. There they find an appropriately medieval village and learn that Merlin kept a library there. The locals have never been inside owing to a curse on anyone who dares enter, but SG-1 finds a way in. Once inside, they find a secret chamber that may reveal the location of the weapon. The SGC, meanwhile, has located the Ori's Supergate. Sam's attempt to get control of it is too late, and four Ori ships make their way through. In the ensuing battle, much of Earth's fleet is destroyed, and the future of several SGC members is left in doubt.—garykmcd

The SG-1 travels to a planet where Merlin's weapon may be hidden. They arrive at a village called Camelot and see a sword in the stone like the legend, and the team is welcomed by the locals and their leader, Meurik. Soon they learn that Merlin left the town many years ago and left his library with a curse to protect the place: the Black Knight would kill whoever entered the library. After convincing the village historian Antonius to help them, they enter the library. Now they have to find the weapon. Out of the blue, they are beamed onto the Odyssey and learn that they have found the Supergate. The group splits, and Daniel and Mitchell return to Camelot to look for the weapon while the Odyssey heads to join the Jaffa and Tok'ra ships to destroy the Supergate. Teal'c goes to a Jaffa ship, and Odyssey receives Asgard Kvasir on board. Then Teal'c goes to a Lucien Alliance vessel to convince Netan to join the allied forces against the Ori. The battle is about to start.—Claudio Carvalho, Rio de Janeiro, Brazil

Since the weapon Merlin once devised against ascended beings seems the human race's best chance to resist or even defeat the Ori, SG-1 travels by Stargate to a medieval society in a place called Camelot where the local Arthurian epic (differerent from Earth's romanticized traditions) confirms its location should be found in a forbidden library guarded by a Black Knight. When they are beamed up to Earth's super-starships about to try stopping the Ori fleet passing a Supergate, Daniel and Colonel Mitchell decide to have themselves beamed back inside the library, but on neither front do things go as expected.—KGF Vissers