Memento (S06E20)

Col. Jack O'Neill is miffed about being taken off SG missions to baby-sit the commander and crew of the Prometheus on her shakedown cruise. But both Gen. Hammond and Gen. Greer feel that SG-1 has valuable experience with both hyperspace travel and this interstellar spacecraft, having already saved it from the Goa'uld and used it to help the Asgard. As it happens, flight commander Col. William Renson isn't too keen on SG-1's being there, either. The ship comes out of hyperspace nine minutes ahead of schedule, the result of a hyperdrive problem. Maj. Samantha Carter explains that when the Naquadria energy levels rise too high, there is a buffer, like a surge protector, that is supposed to prevent instability. However, the buffer is broken. Jonas Quinn checks the ship's sensor log and discovers that the Prometheus had passed through the intense gravity wave of an exploding star while in hyperspace. Jonas notes that, according to the cartouche that lists all the planets with stargates, the Prometheus was fairly close to P3X-744. Col. Renson authorizes using the hyperdrive for a quick burst, theoretically too short for much chance of instability. Carter would use the planet's stargate to travel home, get the supplies she needs, and come back to repair the ship's buffer so that the Prometheus can return to Earth. When they get to P3X-744, the Naquadria reactor goes critical and has to be jettisoned. The resulting electromagnetic pulse further damages the Prometheus and is perceived by the people on the planet below as an attack. They launch missiles in retaliation. Renson orders the missiles shot down, but the ship's weapons control center is offline. O'Neill, on comlink, explains to their attackers that the EMP was an accident and asks them to please not destroy the ship. It works: The missiles self-destruct and the Prometheus is instructed to land by Commander Kalfas of the Tangean security force. Renson and SG-1 meet with Tangean Chairperson Ashwan, who is happy to meet visitors from another world and offers to help SG-1 find the stargate, which they call the "Ring of the Gods." To them it is just a myth, but they let Jonas, Teal'c and Carter go through the Tangean history books to research its whereabouts. Kalfas is not happy about this. He is in political competition with Ashwan, who is increasingly being perceived as weak in matters of civic defense. The arrival of the Prometheus did not help matters much.

Tangean history, however, only goes back 300 years; the "dark age" before that was erased from the record. Jonas and Teal'c meet a Tangean historian who had found some Goa'uld artifacts that led him to believe Horus was his god. According to Teal'c, Horus was Heru-ur — a Goa'uld system lord who'd invaded the Asgard home world of Cimmeria and tried to kidnap the son of his rival, Apophis. It appears Heru-ur had brought the Tangeans from Earth centuries ago, enslaved them, and, after depleting the planet's riches, departed. Among the artifacts is a map leading to where the Tangean stargate is buried. With Ashwan's assistance, SG-1 unearths the stargate and gets it up and running. Then Kalfas and his army unexpectedly arrive to take over. SG-1 needs the Prometheus to overpower Kalfas, but the Tangean has guns aimed at it. Ashwan assures Renson and SG-1 that the Prometheus will not be fired upon. Col. Renson is skeptical until Ashwan boards and puts himself at risk. Ashwan emerges from the Prometheus and makes an eloquent speech to Kalfas' armies about how the stargate is the key to the Tangeans' past and future. He successfully orders the soldiers to lower their weapons and take Kalfas away. Carter can now return to Stargate Command and get the parts needed to repair the Prometheus for its journey home. (Metro-Goldwyn-Mayer (MGM))