Meridian

Meridian is the twenty first episode of the fifth season of Stargate SG-1.

Plot
The episode starts out as SG-1 returns to base, Carter hastily tells General Hammond that Daniel has been exposed to radiation. Hammond asks for an explanation as Daniel and the rest of SG-1 head for the infirmary, meeting a medical team part way there. Daniel cautions them not to touch him and Carter explains that he may still be radioactive. Jack and Teal'c tell Hammond that they did not witness Daniel's exposure and aren't aware of exactly what has transpired. Once Daniel reaches the infirmary Doctor Fraiser asks Carter for details, Sam explains that Daniel was exposed to a device containing an 'Unstable variation of Naquahdah' and that the dosage was lethal.

A briefing is called and Carter explains to General Hammond that the world Langara they were visiting has three superpowers in a situation roughly analogous to that of America in the Cold War, though the countries have yet to develop nuclear weapons. Langara's Stargate is located in Kelowna, one of the three Superpowers. The first of three flashbacks begins, introducing Jonas Quinn as an adviser to the High Minister of Kelowna, the Head of State. Jonas shows SG-1 a high security project he is overseeing, testing of a radioactive isotope called Naquadria for use as a weapon, with the aim of creating a deterrent. The flashback then cuts back to the briefing, and Jack explains that the Kelownans are accusing Daniel of attempting to sabotage their research.

Jack visits Daniel in the infirmary, where Daniel explains that because of the intense exposure to radiation he will begin to die in the next 10-15 hours, and there is no cure. Jack implies a request for help from the Asgard or Tok'ra, but Daniel responds that his life is no more important than anyone else's and they would not go to such lengths for others. Jack changes the topic and asks Daniel directly what happened, but receives the reply "That doesn't matter", but Jack insists. Daniel reveals only that there was an accident and that the scientists working on the project blamed him to avoid repercussions.

Jack speaks to Hammond in his office, where it is explained that the Asgard and Tok'ra cannot be contacted and there are no other feasible options. O'Neill then checks in on Carter in her lab, she informs Jack that she has calculated Naquadria is much more powerful than Naquadah, allowing them to generate enough energy to achieve Hyperspace and Shield technologies. General Hammond decides to send a letter to the Kelownans apologizing and requesting trade for the Naquadria, using Colonel O'Neill as the courier. While on Langara, Jack speaks with Jonas Quinn, appealing to him to admit to his government that Daniel did not attempt sabotage, Quinn replies that he could not clear Daniel's name even if he tried, which would result in the cancellation of the Naquadria project, which Quinn feels is vital to the survival of Kelowna.

Back on Earth, Janet Fraiser tells Carter that there's nothing she can do for Daniel, except sedatives and painkillers. Carter volunteers to attempt to heal Daniel with a Goa'uld Healing Device. The attempt causes Daniel's health to deteriorate. While the doctors try to stabilize Daniel's condition, he slips into a sort of dream, where a suited woman approaches him in the gate room with a cryptic message.

Jack visits Daniel while he is conscious, and tells Daniel that he won't let the Kelownans defame him as a saboteur, Daniel inquires as to why, and Jack admits that he respects and admires Daniel. Daniel re-enters his 'dream' and realizes the woman is Oma Desala. She speaks in Zen koans and encourages him to ascend in characteristic roundabout way. Daniel asks how, and Oma tells him to "Release [his] burden", Daniel says he has released his burden and asks for the next step, but Oma just provides another Zen koan and Daniel wryly comments that he didn't expect ascension to be easy.

Meanwhile, Jonas Quinn has had a change of heart after he realizes how destructive a Naquadria bomb would be. Jonas brings an amount of Naquadria with him and informs Jack that he has told his government the truth and then defected. The second flashback occurs, and Daniel is observing the naquadria experiment with Jonas. Suddenly the experiment goes awry and enormous amounts of hard radiation are released. The researchers flee as the naquadria begins to go supercritical (reaching critical mass). Daniel breaks through the glass separating the observation room from the lab and removes the top half of the device with his bare hands, exposing himself to radiation in the process of preventing a nuclear catastrophe. (This incident is much likely based on Louis Slotin's one, except it was plutonium that caused the radiation poisoning instead of fictional naquadria).

The scene changes to Daniel conversing with Oma in the dream-gate room, where Daniel confesses that he feels his entire life has been a failure. Carter intrudes in the dream-gate room and tells Daniel how his perspective of life has changed her and many others. Oma Desala tells Daniel that to ascend, one must believe they are worthy of it. Daniel replies heavily that they have a large obstacle in the path of his ascension. Teal'c then expresses to Daniel what great effect he has had on the course of Teal'c's life and the course of history as a whole. Daniel is now in a dream-version of his office, where Oma asks him why he feels like a failure, Daniel explains he felt he was unable to make a real difference, but concedes that he was able to make a small difference occasionally. As Daniel battles with his own inadequacy, Jacob Carter/Selmak arrives and begins healing Daniel with the Goa'uld Healing Device, but Daniel intervenes: he pulls Jack into his dream and explains that he has decided to ascend. Jack stops Jacob/Selmak and Daniel ascends.