SGC receive a distress call through the gate sent by the Eurondans, a civilisation that has traced its roots back to Earth. When SG-1 go to see what they can do to help they find a race technologically more advanced than Earth. They are willing to exchange their advanced technology for Earth's help in defeating their enemy. Jack is very eager to accept but Daniel has reservations.

After they tell Jack not to bring Teal'c becuase of what he represents, Jack starts to wonder about them, and makes a startling discovery that will change the relationship between the two worlds.

A Tok'ra scientist Anise/Freya brings with her some devices that both the Tok'ra and Goa'uld have been searching for for years. They are said to make the wearer superhuman but won't work with the Tok'ra, probably because of their symbiot. She wants O'Neill, Carter and Jackson to try them out.
As the effects become apparent Dr Fraiser becomes concerned and a change comes over the 3. It is then the Tok'ra reveal their real purpose.

Teal'c is reunited with a lost love, Shan'auc who is a Jaffa Priestess who says she's discovered a way to defeat the Goa'uld. She claims to be able to communicate with her symbiot, and to have taught it right from wrong. She tells them that her host has become mature enough to take a host and that it wants to be part of the Tok'ra. SG1 agree and take her to the Tok'ra who give the symbiote a new host and give Shan'auc another symbiote. However, after a while Shan'auc is found dead and they beleive its because her body rejected the new symbiote.

After Teal'c tries to communicate with the Goa'uld inside of him, he learns that they are evil and will not change. He also learns who really killed Shan'auc.

While trying to formalise a treaty with the Tok'ra, a meeting is arranged between the Head of the Tok'ra Council, Per'sus,and the President of the US. When Major Graham makes an assassination attempt on Per'sus Anise says she believes the Goa'uld had implanted the instruction for the assassination there (he had become a Zatark) , as she's seen similar cases recently, problem is it's virtually indetectable. Anise thinks she has a device which can help but it's a prototype and could have unpleasant side effects. Martouf is concerned about the use of the device as the Goa'uld mind control has not been proved, as are the SGC, but failing any other explanations and given the importance of the talks they agree to let Anise test all of SGC.

However, when they test Sam and Jack they find that they seem to have "false" memories and they have to be kept under guard. As the time of the meeting comes closer, Hammond orders them both to be put into a deep sleep until they can find a cure, as if they cannot complete their mission they will kill themselves. However, Jack volunteers to be a guienie pig and test out the only machine that can cure them, however the last time it was tried the crewmen killed herself. Just as he is about to start the process, Sam remembers a detail which they both missed out and is able to be retested and this time they are both cleared.

However, if they aren't the "Zatarks" then who is?

SGC find they cannot open the Stargate and then the Russians contact them. The SGC find that the russions have discovered original stargate which was thought lost when Thor's ship crashed into the sea. They ask for help, as they can't turn off there Stargate and have lost contact with their people. SG-1 go to Siberia to discover what happened to the base full of people who'd been experimenting on the gate. They're met by a Russian scientist who seem to know all about SGC, SG-1 and the Stargate Project. When they get to the Russian base everyone's dead, the gate can't be closed and is connected to a world covered in water.

They also discover the traitor which had revealed the information to the Russians. Whilst trying to get the stargate shut down, the scientist along with Sam and Daniel get stuck in the submarine with no control and the water pressure rising. Jack must figure out what is going on and save Sams life.

A world is discovered which SGC think is the homeworld of the Goa'uld, and Unas. Daniel is helping on a dig with Rothman and SG-11 when he is captured by a native Unas. Rothman goes back to SGC and the rest of SG-1 mount a rescue mission. Meanwhile Daniel is using his diplomacy and language skills to form a bond with the young aboriginal Unas, but he thinks he is some sort of right of passage trophy and as such is being taken away to be killed. Meanwhile the rest of SG-1 are trying to find him on a planet full of Goa'uld larva. The problem rises when Teal'c realises that any one of them could haave been taken over by the Goa'uld and there is no way to be sure.

SG-1 and SGC help relocate some people to a new world when they find that they are ultra sensitive to certain radiation and the world they are currently on is making them go blind. Unfortunately, the planet they relocate them to has already been picked out by another civilisation as the ideal world for them, and just after SG-1 help the people to move a ship arrives and starts terraforming the world - a change which is poisonous to the people who have just relocated there! SG-1 have to help negotiate with the new race and find a solution which is acceptable to all.

However, it seems that the ship can only terraform one planet, and now that the process has begun it cannot stop. Jack however, wants to help those people anyway they can and after General Hammond refuses to give military help, he decides to use a Naquadah bomb to blow the ship up. Daniel on the other hand is torn between the two people as he realises that if the ship is destroyed it will destroy a whole civilisation, but if he lets him terraform the planet then it will destroy many towns and villages and many people. However, Daniel gets anoter solution and they find the Original planet that the people had come from so that they could send them there via the ship so both people would be happy.

Daniel, Teal'c, Sam and Jack are all working underground on a glacier like planet with no recolection of their real identities of their lifes or even the fact that they were once friends. They start realising something is wrong when Teal'c's symbiot helps him recover his memory and he tells them that they are all friends and part of SG-1. Teal'c is taken away suffering from "night sickness" and when he returns he can remember nothing of what he had said. However, Daniel starts having weird dreams which relate to what Teal'c said, and so they try to remember his past, which makes him realise that somethins is amiss. He approaches Sam and Jack and they all start to remember, in the meantime Teal'c is taken ill and has dissapeared.

Back at SGC General Hammond is pulling out all the stops to try to locate them. However the people that live on the planet above say that they went into the blizzard and were surely killed. When an SG team go to find them, they realise that there is no way that Jack would have wanted to go out in the storm.

Slowly but surely the teams memories start to return, however when Teal'c becomes seriously ill, the person in charge of the facillity who does not see eye to eye with the leader of the planet brings the rest of the team and tells them the truth in hopes that they can save him. However, she does not know that the leader had been watching her, and just before they can leave he and his security team arrives.

However, Teal'c who had put himself into a deep state of Kel'no'reem wakes up to help the team over power the people. But before leaving they tell the people working like slaves the truth that the a city exists within a dome structure for which they are generating power.

SG-1 must investigate a conspiracy nut named Martin who has classified information about the Stargate project. Jack is sent to meet him and they discover he also believes he's an alien and claims to have vague memories of an alien life. However, when they go to search his house, they find that hes been taking alot of un-needed medicine and find evidence of bugs in his house.

When Sam and Daniel talk to his doctor he gives them an adress of his relatives, however when they get there they find that it is a trap, and find themselves in the hands of the doctor and his associates. However, when Martin's memories start coming back slowly, he remembers where his space ship is, and is able to show Jack confirming his story. However, they soon find that the men that have kidnapped Sam and Daniel are not what they seem to be either when it becomes apparant that they were with Martin on the ship.

Humans make another small leap towards becoming a world capable of protecting itself with the creation of the X-301 “Intercept”, a revolutionary defence platform based on technology from two Goa'uld Death Gliders merged with US Air Force Design Technology. The features recognized most in its design is the ship’s ability to attain high speeds, quick and precise maneuverability due to the cancelling of inertia upon the fighter, and two ‘Slammer’ missiles with enhanced warheads through the use of Naquada.

Needless to say, when General Hammond brought a Lieutenant General from the Pentagon, he was impressed. Although questioning whether or not the fighter will be an effective defence against the Goa'uld, the Lieutenant General is pleased with the overall performance and returns with General Hammond to the SGC to watch a test run. It will be against a drone in a live fire fight.

However, soon after the beginning of the test, the X-301 takes a sudden upwards accent into orbit and straight into space, though no act of either Teal’c or O’Neill. They lose all control over many systems, including navigation. Eventually, after speeding away from Earth at a massive rate of speed, the navigation system cuts out, leaving the fighter adrift. Teal’c then attempts to restart the vessel, only to get a recorded message of Apophis, telling him that the traitor will die in the cold of space.

Already, the time lag between the X-301 and Earth is large, already three minutes, since the X-301 is still moving away from Earth at one million miles and hour, even with all thruster systems cut. Sam Carter believes it to be a sort of recall device, which will bring the Glider back to the homeworld of Apophis. It is decided that they will contact any of their space faring allies for assistance.

Soon, however, Carter comes up with an idea which involved Sling-shooting around Jupiter, which would, unfortunately, require thrusters, until Jack O’Neill mentions that they have the two missiles on board, and asks if it would be possible to override the release mechanism, allowing them to use the thrust from the missiles to move the vessel. Since they installed the entire firing system, they have total control over it. Hammond and Davis agree to try the idea.

Unfortunately for them, the release mechanism can’t hold onto the missile long enough, and fails, releasing the missile, which spirals out of control and runs out of power, and drops into the X-301’s path, impacting the vessel. It does power to their life support, dropping available life support from days down to twelve hours, and throwing them off course towards the Oort Cloud. None of the available allies have an nearby ships, but the Tok’ra Anise mentions that they have an operative on a mission close to Earth, and that he is very close to them, then says she has done them a favor by telling them this much. They believe that it is Jacob Carter/Selmak that she is speaking of, and finds the closest planet until Goat’old control.

They go to the mining planet, where they are almost immediately picked up by Jacob Carter. Annoyed that his plan to blow apart an area of the planet is now useless, his anger lessens when he learns of the plight of the two stranded pilots, and sets course for Earth at 122% of the maximum speed of the scout ship he is on, eventually damaging them and dropping them into Goat’old controlled space, in front of two Goat’old vessels. Thankfully, they escape, and make it to Earth’s solar system.

O’Neill is suffering from Oxygen deprivation, and Teal’c had long ago put himself into a deep trance to preserve oxygen. They are forced to release the buckles and open the cockpit to space to get clear of the ship so that the ring transporter can bring them up, safe and sound.

Daniel reads of the death of his Professor & mentor in the papers and goes to attend his funeral. However, when he attends the funeral he gets drawn back to his academic roots and the apparent awakening of an ancient curse.

However, as things unfold, it seems that the problem is Goa'uld based. A jar is found with a Goa'uld symbiote inside, and to make matters worse, there were two and the other jar is no where to be found.

When Teal'c returns to Chu'lak to recruit some of Aphophis's former Jaffa to help in the fight against Goa'uld control he is captured and tortured. Meanwhile, Jacob tells SGC of a planned meeting between Apophis and Heru'ur who might decide to form an alliance. He tells them that if this were to happen they would be strong enough to overthrow the system lords, and so they go to try and stop the treaty.

However, they still do not know that Teal'c has been captured, and worst of all he is on Heru'urs ship. They are surprised to find that for the Alliance, Heru'ur wants to present Teal'c as a gift to Apophis. When the talks between them start the team have very little time to put their plan into motion and to stop the alliance from happenening. However, what they didn't expect was Anubis to come prepared with an army of cloaked mother ships, and it seems that this is the first time anyones been able to cloak a fleet that large.

Things look bad as Heru'ur's army is crippled however, when they spot a death glider escaping Heru'urs mothership they are relieved to find that it is Teal'c who had escaped thanks to another Jaffa who now sees that the Goa'uld are no gods.

General Hammond announces his intention to retire and step down as head of SGC. When the new commander, Major General Bauer, arrives he is every bit as bad as SG-1 feared. He splits up the team, gets Sam to do a very dangerous experiment which endangers all of SGC and threatens to fire Jack. Jack takes gardening leave and goes to investigate Hammond's mysterious desire to suddenly "retire" this takes him back into the company of Maybourne and Senator Kinsey.

It's the year 2010, Earth is at peace having made friends with an alien race called the Aschen who share their technology with us. Technology so advanced that all disease and hunger, as well as threat from Goa'uld is eliminated. A paradise. But when Sam finds out why she is unable to have children they discover that "paradise" is not all it's cracked up to be.

What they thought was their allies turns out to be conqueres that have patience, and are waiting for the people of Earth to wipe themselves out. Kinsey is now president of the United states and so Sam must find a way to change what has happened.

With the use of the Aschen technology they plan to send a message back through time, however to do this they must calculate the time of the solar flare and must get a GDO so they can send a signal to open the Iris. To do this SG1 team up once more, with the intent of changing the past, to save the future.

SG-1 get summoned to Abydos by Kasuf, Sha're's father as he had heard her name whispered in the wind. When they get there they find Harsesis child, however he is not the child that he should be but a boy of about 8 called Shifu. He is full of Eastern wisdom but can't remeber the knowldege of the Goa'uld as Oma Desala has represssed the memories. Daniel tells him about his mother Sha're and he teaches Daniel just why it would be a bad idea for anyone human to have the genetic knowledge of the Gao'uld.

SG-1 encounters problems when they discover a Goa'uld pleasure palace with an addictive room of light. When one of the first people to see it returns to the SGC it seems that he can't resist it, and doesn't even wait for the wormhole to be formed and kills him self. Things become worse when SG1 become addicted and now must find a way to turn it off, however while at the planet they discover a little boy who seems to have been there for a long time.

Carter must help keep a promising young cadet from throwing away a future in the Airforce, she feels she's got a great mind and could be very useful at SGC. She persuades General Hammond to give her clearance to go to a planet Jack and Teal'c are on protecting some scientists.

However, when they are at the planet the realise that the native life forms that live there are not happy about having one of their fellow lifeforms trapped by the scientists, and start to attack. Things become worse when a swarm of them appear and the only way off the planet is through the stargate.

An alien lifeform manages to infect SGC via a MALP's radio signal. It infects all the computers and just when they think they have it beat, it infects Sam. They need to find out what it wants and how to get rid of it, but can they do it before they lose Sam for good?

SG-1 go to a planet where they are captured by the naitves working with Goa'uld. The native Juna people are angry as SG-1 have visited them before and helped them to overthrow Heru'ur, telling them to bury the gate and they would then be safe. However, Cronos came in a ship and is now in control of the planet. Jack escapes but the other 3 are taken before Cronos and forces one of them to kil Daniel. However, when he carries out the order he is surprised to find that Daniel is not human.

It turns out that they are in fact the duplicates that were ment to have buried the gate in the episode Tin Man. When Harlan the creator of the duplicates goes to SGC they learn that the Juna people are now ruled by Cronos. They agree to go and help them, to overthrow Cronos once and for all.

General Hammond agrees to lend the Tok'ra the ship SG-1 captured so they can move the Stargate to a planet so the Goa'uld will not have the address for it, so the Tok'ra will then be able to make a more permanent base. SG-1 go along to check all goes well. The Tok'ra let Tanith know they know he's a spy of Apophis's but he escapes and Aphophis comes with ships to destroy the Tok'ra before they are able to move.

Sam and Jacob come up with a plan to destroy Apophis's fleet by destroying the solar system. To do this they must dial the wormhole planet and send it into the systems sun which would end up creating a blast that would destroy anythign in the area.

However, things don't go to well with Jack and Teal'c's attempts to capture Tanith and with time running out Jack has to leave Teal'c behind. Things go from bad to worse when whilst riding the systems explosive waves, they end up light years away. Jacob realises that the hyperdrive isn't working properly and even if it did, it would take over 100 years to reach Earth at maximum hyperdrive. Then to makes matters worse even more, Apophis comes and, it seems he was also able to escape.