Daniel and Vala must deal with the new born child (Vala's), who is aging rapidly to lead the Ori's Crusade.

Daniel discovers a gate address that might lead them to the weapon they must find to fight against the Ori. They travel to the planet in question, but find all the people in the village have died in their sleep a long time ago. Plus, it seems all the animal life around the village has died too. Soon the team realizes that they are being affected by the same disease whichhuged the population of the planet. They must stay wait at all costs, until they can fid a cure Meanwhile, Vala stays behind at Stargate Command in order to take a psyche test. If she passes, she can join SG-1 on its off world missions. However, things go badly, as she tries to game the test by studying how to respond to the potential questions she might be asked. Agent Richard Woolsey offers Vala a solution to her dilemma, but can she accept doing what he asks in return?

SG-1 travels on the Earth ship Odyssey to Atlantis to both try to dial in the 'super gate' nearby, and to let Daniel continue his search for the anti-Ori weapon while staying at Atlantis. Things get tense as an Ori ship approaches Teal'c's position at the super gate, just as a Wraith hive ship approaches the Odyssey's position in the Pegasus galaxy, where they are trying to activate a gate connection to the super gate back in the Milky Way.

The villain Ba'al makes a surprise offer to Stargate Command; he will help them locate the Ancient's super weapon, if they deal with his now troublesome clones. Although highly skeptical, they proceed to gather the clones up. Each clone, however, claims to be the real Baal. Once the clones are securely locked away in Stargate Command, Ba'al makes his move. There is something that he desperately needs, the access codes to the SGC's most sensitive files. Plus, Ba'al may have found an insider who can help him find the desired information.

As Col. Mitchell arrives at Gen. Landry's retreat, where the rest of the team are to bond with the General, the others are diverted to fight an invisible man-eating creature on another planet, and to determine if it is connected to the Ori. As Mitchell and Landry try to co-exist alone together, a storm washes out the only accessible roadway to their cabin. They soon find they must also fight off the same type of invisible man-eating creature that SG-1 has been checking on off-world.

SG-1 gets pulled back into Martin Lloyd's world when he convinces the powers that be to let him talk to the team, as he is about to revive the Wormhole X-treme TV series as a big screen movie. He needs help with ideas from SG-1 to try to make the movie 'real.' The team fights this, but Gen. Landry orders them to help, but says he will get them out of the meeting as soon as possible. However, when the General drags them out of the meeting, the gate activation breaks down, leaving them stranded with time to try to help Martin out with his project, to their dismay.

The new leadership among the Jaffa decides to use the powerful weapon on Dakara to wipe out entire planetary life on other worlds in order to capture and build a fleet of Ori ships of their own. However, they have chosen a planet where the Ori / Vala offspring and SG-1 are on. Which will prove to be the more lethal, the Jaffa in their quest for Ori ships, or Vala's offspring, who is determined to find and stop the Jaffa's weapon?

Vala's past comes back to haunt her, as a Goa'uld named Athena, a past enemy, and then a reluctant ally of Vala's past Goa'uld host, captures her to try to recover information that she may have retained from her past host, about a treasure map that could lead to great riches. When an SG team locates and attempts a rescue Vala, an arrant Zat shot causes Vala to lose all her past memories. Vala, now not knowing who anyone is, escapes during the chaos caused by the rescue, and moments later the site she was held at explodes, leaving many to believe she is now dead. As Vala roams the streets not knowing who she is, Daniel continues to believe she has survived, and pushes the hunt to find her. However, Athena, also believing Vala is alive, also continues her hunt to find Vala. The question is who will find Vala first?

The Earth ship Odyssey, with Carter aboard, gets tricked into a trap near a neutron star, only to find itself in a mine field when they try to escape several attacking Goa'uld Mother-ships. This leads to Vala and Jackson being kidnapped when the rest of the team goes in search of the Odyssey. It turns out a breakaway faction of the Lucian Alliance, lead by the leader, Anateo, is responsible. Anateo is attempting to capture the entire team, and then turn them and the ship over to Lucian people in a bid to take over control of the Alliance from the its leader, Netan. While the captured crew makes plans to take back over the Odyssey, Mitchell goes undercover as a cold blooded hugger, in order to find out what Netan might know.

Daniel, with some insight from a dream Vala has had, determines the possible planet which might be the location of the Sangraal; the anti-Ori weapon. The search, however, turns into a maze of a journey where they must follow the prophesied path, as others try to beat them to their goal. Those dogging their path are both Baal and Adria, separately. Can the team survive the numerous traps set long ago by Merlin, the treachery of Baal and his troops, and the cunning guile of Adria to find the Sangraal in order to save humanity?

In the search for the Sangraal, SG-1 comes across Merlin himself frozen in hibernation. With Adria and the Ori tracking them down, SG-1 must help Merlin complete the weapon before it's too late.

SG-1 are ordered to hide the population of a planet in another dimension to protect them from the Ori, using Merlin's Ancient device. However, when the device fails the Ori capture the villagers, Vala is reunited with her husband Tomin, Teal'c risks betrayal by the locals, and Mitchell and a critically-injured Sam manage to hide one building. But time is running out for them all...

While working on Merlin's phasing device and using a protective force shield, Sam is shunted into a parallel dimension where her counterpart, Major Sam Carter, was trying to tap into alternate dimensions for energy. Trapped in a world where Major Lorne commands SG-1, General Hammond runs SGC, Hank Landry is President, and Rodney McKay is her ex-husband, Sam must work with them to protect Earth from the Ori. However, once she succeeds she finds they're not willing to let her go home.

SG-1 encounters a planet that a Prior has visited yet did not make any threats to the village in the event they do not bow down to the Ori. The team discovers this Prior is their own Daniel Jackson.

After the SG-1 team destroys a Lucian Alliance cargo ship filled with illicit drugs, a bounty is placed on capturing the entire team, which in turn sets several alien bounty hunters against each other to claim the reward. Mitchell reluctantly agrees to take Vala to his upcoming High School reunion, where is causes quite a stir.

When the team arrive at an alien museum and are mistaken for rebels, they are forced to stage a bogus hostage situation to buy enough time to escape from the museum and the army gathering outside. However, an overeager security guard takes matters into his own hands, complicating matters.

When a terrorist attacks a Jaffa summit, Teal'c strikes out on a quest for revenge

To Vala's dismay, her father Jacek contacts Stargate Command claiming to have knowledge of Arkad's ships that were enroute to bomb Earth when he washuged by Teal'c. With it likely the mercenaries still believing they are to follow through with their bombings, SG Command is forced to agree to deal with Jacek. Regardless of Vala's warnings about Jacek's devious and scamming nature, General Landry has no option but to grant him sanctuary on Earth after his information proves to be true. Jacek, trying to assimilate into Earth's population, shows no inclination of giving up his scamming ways. While SG struggles to figure out what to do with him, Vala continually rebukes every attempt her father makes at reconciliation with his estranged daughter. Wearing down SG's patience, and Vala's resolve, they discover Jacek trying to break his home arrest and catch him consorting with one of Arkad's Jaffa splinter cells stationed on Earth. Claiming he was just trying to stop another of Arkad's ships destined to destroy Cheyenne Mountain and the Stargate, the team must put again put their trust in Jacek to help them locate the cloaked ship and disable it before it can explode.

Vala is forced to leave SG-1 when her prophetic dreams of the location of Merlin's treasure lead SG teams into a trap. Adria finds her mother and wants the now independent Vala to take her to the treasure. However, SG-1 and Baal have plans of their own.

When the Asgard decide to share all their knowledge and technology with Earth, they do so by incorporating that knowledge and technology into the Odyssey. However, the incorporated Asgard systems become a tracking beacon for the Ori and every time the Odyssey drops out of hyperspace it is attacked by the Ori. Finally, after numerous attacks, when just about to be destroyed, Carter uses the Asgard time dilation technology to slow down time in hopes of finding enough time to plan an escape from their certain destruction. However, can Carter figure out the impossible escape? And just how long will it take?