Moebius (Stargate SG-1)

Samantha "Sam" Carter reveals the existence of the Daedalus: a new Earth-built battlecruiser which is capable of reaching the Pegasus Galaxy and is larger and more advanced than the Prometheus. Daniel Jackson learns of Catherine Langford's death and, after her funeral, receives Catherine's collection of documents and artifacts relating to the Stargate program. From one book in the collection, Daniel learns of the former location of a Zero Point Module (ZPM) in Ancient Egypt. Daniel and Carter persuade Jack O'Neill to use the time travel capabilities of the Puddle Jumper they found to travel back and take the ZPM, assuming that Ra never knew of its purpose.

Once they arrive in 3000 B.C., they join in an offering to Ra and witness his cold-blooded murder of an Egyptian making the offering. Teal'c disguises himself as a Horus Jaffa and retrieves the ZPM from Ra's treasury. However, Ra's Jaffa discover the cloaked Jumper after a sandstorm covers it in sand. Unwilling to upset the future by fighting the Jaffa to get the Jumper back, SG-1 decides to live out the rest of their lives in the past, knowing that the rebellion that overthrew Ra will eventually happen. However, an alternate timeline is created in which the Stargate was never discovered and everything SG-1 have done for the last eight years never happened.

In this timeline, alternate Daniel is teaching English as a second language, alternate Carter spends her time double-checking other scientists' work, alternate O'Neill is retired from the military and alternate Teal'c is still the First Prime of Apophis. Alternate Daniel and alternate Carter are contacted by the Air Force and brought to Cheyenne Mountain.

At Cheyenne Mountain, George Hammond informs alternate Carter and alternate Daniel that archaeologists found a video camera in a vacuum-sealed canopic jar at a dig in Giza. The video contains a recording of the original SG-1, explaining who they are and what they were doing, as well as a number of things that are true in their timeline, such as recent political events, Presidents and personal details. Their plan is that if things have changed in the future, then SG-1's alternative selves will travel back in time and fix the past.

An expedition team is sent to find the Giza Stargate, but find nothing. Instead, they discover that the original Daniel left a tablet where the gate should have been, inscribed with an obscure dialect of Egyptian that only alternate Daniel can read. It reveals that the original SG-1 instigated a successful rebellion against the Ra of 3000 BC. However, this caused him to leave Earth with the Stargate. However, they do find the Puddle Jumper, and alternate Daniel and alternate Carter figure out how to find the Antarctic Stargate. A team is assembled to go through the Stargate to recruit alternate Teal'c under the instruction of the Daniel and Carter on the tape. Alternate Daniel and alternate Carter are not going to be on this team.

The scientists working on the recovered Alternate-Puddle Jumper cannot make it work because they do not have the ATA gene. Alternate-O'Neill is called in to operate the Jumper and lead the team through the Stargate to find alternate Teal'c, and agrees that alternate Daniel and alternate Carter are to join the team through the Stargate.

On Chulak, SG-1 are caught by Jaffa loyal to Apophis and imprisoned. Alternate Teal'c defects to their cause and helps them escape but alternate Daniel was made a Goa'uld spy by Apophis and is killed by Teal'c. They escape in the Puddle Jumper, but are chased and damaged by Death Gliders. Unaware of the jumper's cloaking capacity, they believe that only way they can survive is to time-travel. They travel back to 3000 B.C. and use the Stargate to pass from Chulak to Ancient Egypt where the original versions of SG-1 were stranded and where Ra is still alive and ruling.

The original SG-1 attempted the rebellion because O'Neill and Teal'c did not want to stay and O'Neill, Carter and Teal'c were killed when it failed. Daniel, the only survivor, meets with alternate Carter, alternate O'Neill and alternate Teal'c. He has not yet made the tablet detailing the second successful rebellion attempt because it hasn't happened yet. This means that his current plans with the underground of the local populace are destined to succeed, however they lead to the Stargate being removed from Earth by Ra. The plan is to instigate the rebellion, thus diverting Ra's attention, and secure the Stargate to where it was originally buried, allowing the original timeline to evolve as it did.

The rebellion ultimately succeeds, but not before alternate Carter and alternate-O'Neill show their feelings for each other with a kiss, uncertain if they will survive. Ra's Jaffa surrender, outnumbered by the staff- and zat-armed Egyptians. The alternate SG-1 bury the videotape, along with the ZPM, for the SG-1 of the future to find. The alternate-SG-1 and Daniel from the original SG-1 (of 3000 BC) live out the rest of their lives in Ancient Egypt.

The original SG-1 of the present day receive the videotape and the ZPM left for them a few weeks before they were to go back in time. As the timeline has been restored, they have no reason to go back in time, and they've gained a ZPM free of charge. The episode ends with SG-1 at O'Neill's cabin, fishing, in a scene identical to the end of "Threads", except there are now fish in Jack's pond.