Window of Opportunity (Stargate SG-1) - Plot

Plot

On a mission on P4X-639, a planet experiencing strong solar activity, the SG-1 team encounters an alien archaeologist named Malikai (Robin Mossley). When a geomagnetic disturbance hits its peak, the Stargate activates simultaneously on the planet and on Earth, and a flash strikes Malikai, Colonel O'Neill (Richard Dean Anderson) and Teal'c (Christopher Judge) near an Ancient altar. Moments later, O'Neill finds himself in the Stargate Command (SGC) cafeteria in the middle of a breakfast conversation with Dr. Daniel Jackson (Michael Shanks) and Major Carter (Amanda Tapping), who claim to have no knowledge of the planet. O'Neill and Teal'c later express familiarity with the events, and they are checked and certified to be in perfect health. Before SG-1 can resume their planned mission to the planet, an unscheduled offworld activation of the Earth Stargate, accompanied by flashes, transports O'Neill back to breakfast.

While the events at the SGC repeat themselves, Daniel makes first progress in the translation of writings in the photos of the ancient altar. SG-1 return to the planet where Malikai lets slip he too remembers what's happening, but O'Neill finds himself back at breakfast before the altar's activation can be stopped. With the help of O'Neill's and Teal'c's explanations, Carter devises a plan to break the time loop by preventing an incoming wormhole, which fails. Meanwhile, Daniel attempts to translate the altar's writing loop after loop, but his memory is reset each time along with everyone else's, and he cannot possibly translate it all within just a few hours. Ultimately, O'Neill and Teal'c realize the only solution is to learn and remember the alien language themselves. After many loops of teaching, Daniel makes an offhand remark about events that occur during each loop having no consequences once the loop is over, which inspires O'Neill and Teal'c to indulge in wildly outrageous behaviour as a means of dealing with the boredom and frustration of being caught in repeating time. O'Neill and Teal'c play golf through the active Stargate, Teal'c takes action against the painful starts of his loops, O'Neill tries pottery-making, bicycles through the base, and just before the end of one loop, resigns from the Air Force for the sole purpose of grabbing Carter and kissing her.

After what is later believed to have been at least three months, Daniel is finally able to reconstruct the planet's history with the finished translations: the Ancients had attempted to escape a mysterious plague by building a time machine but never got it to work properly. Upon returning to the planet, SG-1 learn of the death of Malikai's wife, whom Malikai wants to visit in the past with the help of the time machine. O'Neill's experience of his son's death convinces Malikai to shut down the device before yet another new loop can start. Back at the SGC, O'Neill, Carter, and Daniel have their first breakfast after the loops, and O'Neill answers Daniel's question about unusual activities in the loops with a long look at Carter.