In an alternate timeline version of the year 2010, the Stargate program has been made public, and Earth has formed an alliance with the Aschen, who helped wipe out the Goa'uld and provided them with numerous advanced technologies. Soon, Samantha Carter learns that she cannot conceive a child, and realizes the Aschen have something to do with it.
The episode begins with Samantha Carter breakfasting with her husband Joseph Faxon as they discuss their fertility problems. They also mention the Aschen, an advanced civilization who possess a very high grade of medical and other technology.
It turns out that the year is 2010, a 10-year jump into the future from the previous episode. Earth has transformed into a seeming paradise of long life and perfect health thanks to an alliance with the Aschen Confederation. It is the 10-year anniversary of SG-1's first encountering the Aschen, and there is going to be a ceremony commemorating the event. The Stargate now serves as a public gateway to other worlds and stands in the J.R. Reed Space Terminal. With the help of the Aschen, the Goa'uld have been defeated; the President of the United States is SG-1 nemesis Robert Kinsey. During the ten year anniversary ceremonies, the former SG-1 members are all present—minus Jack O'Neill. It also turns out that Major General George S. Hammond is dead.
At this point in time, Sam and her husband, Ambassador Joseph Faxon, are trying to get pregnant, but so far no luck. Their doctor, an Aschen, says there's nothing wrong with either of them and that they should just keep trying. When she tells Dr. Janet Fraiser, Janet asks Sam to come by her office for an examination. Janet mentions that she is bored, given the near absence of disease thanks to Aschen medical technology. Sam agrees to be examined by her, and Janet makes a shocking discovery: Sam has been sterilized. She'll never be able to have children. Sam is devastated, not only because she can't have children, but because her Aschen doctor lied to her by telling her there was nothing wrong with her. Both wonder if this problem has occurred anywhere else in the world. They use the Aschen computer at Sam's lab to do a search.
Sam and Janet soon discover a dark secret: the Aschen have made over 90% of humans infertile, allowing them to bloodlessly take over the earth. They appear to have killed General Hammond when he became suspicious.
The former members of Stargate Command and SG-1 realize that it will be impossible to defeat the Aschen, so their best hope of victory lies in preventing Earth from ever meeting the Aschen. Using the advanced sensors the Aschen have given Earth, they pinpoint when a massive solar flare will happen, allowing them to repeat the same form of time travel they used previously to travel to and from 1969. They plan to send a warning to the past, using the centrally located, very public, Aschen-controlled Stargate.
First, they must go to great lengths to obtain a GDO in order to cause Stargate Command to open the Iris. In the course of this, Sam discovers that her husband knew about the Aschen plan to decrease human fertility, though they had told him they would only make 1/3 of the population infertile. In contrast, O'Neill never trusted the Aschen, and is bitter that his word was ignored. After initially rebuffing the former SG-1 team when they ask for his help, he joins them in carrying out their plan. Sam must ask her husband, who is an ambassador to the Aschen, to steal it for them, because the only remaining GDO is in the Oval Office, on President Kinsey's desk. Joe agrees to aid them in exchange for the paternalistic promise that Carter be kept out of the final assault on the Stargate.
To get control of the Stargate, they enlist the help of Teal'c and another Jaffa. They are able to break through the strong defense measures surrounding the Stargate and dial the gate. However, as the former SG-1 members try to send their hand-written note through the gate, they are killed one by one, with each getting a bit closer to the gate. After the deaths of Teal'c, Jack, and Dr. Daniel Jackson, Sam breaks away from her husband and rushes to the Stargate. As she is cut down by the lasers, she manages to throw the bloodied note, written by O'Neill, through the gate. Janet is the only survivor as she had traveled to Chulak to set things up with Teal'c before the attack began.
Back in 2000, Stargate Command receives an incoming transmission, accompanied by an SG-1 IDC, and through the gate comes a small, crumpled paper note. Written on it, in Colonel Jack O'Neill's handwriting (and with spots of O'Neill's blood on it as well), is a simple message: "UNDER NO CIRCUMSTANCES GO TO P4C-970, COLONEL JACK O'NEILL". Major General George S. Hammond orders P4C-970 locked out of the dialing computer to prevent the planet from ever being contacted.
Alternate timeline; Anti-aging vaccine; Aschen; Aschen computer; Aschen Confederation; Aschen holographic projector; Aschen medicine; Aschen monitoring satellite; Aschen Prime; Aschen technology; Aschen transporter; Chulak; Defense drone; Dog; Embarkation room; Fishing; GDO; Grey Cup; Heart attack; J.R. Reed Space Terminal; Jupiter; Level 28; O'Neill's cabin; Oval Office; Sol; Solar flare; Stargate Command armory; Super Bowl; Teal'c's friend; Time travel; Tok'ra; Tollan; Washington D.C.; White House; World Series; Zat'nik'tel
Carter: I'm fine, right?
Fraiser: Sam, I don't know how the Aschen doctor could have missed it, and frankly I don't think he possibly could have.
Fraiser: You can't have children.
Waitress: Will there be anything else?
Jackson: Apparently not...
O'Neill: (imitating a tour guide in a museum that was once the SGC) "...and we're walking."
(Teal'c and a Jaffa come out of the Gate holding staff weapons)
Dialer: I'm sorry, sir, but weapons are not allowed.
Teal'c: We carry these for ceremonial purposes only.
Dialer: I'm sorry, but you'll have to let me have it.
Teal'c: Very well.
(Teal'c shoots the dialer with his staff weapon)
(referring to the GDO Joe has just stolen from the President's office)
Joe: What are you gonna do with it?
O'Neill: Send a message.
Joe: To who?
O'Neill: To "whom."
Daniel: Uh... the sun's beeping.
(A note comes through the Stargate)
Hammond: What is it?
O'Neill: You tell me.
Jackson: “Under no circumstances go to P4C-970. Colonel Jack O'Neill.” That looks like your handwriting.
O'Neill: It is my handwriting. And it's my signature.
Teal'c: Though you sent no such note?
Fraiser: Sir, may I? (she takes the note) That looks like blood, sir.
Hammond: Have it analyzed.
O'Neill: General, wasn't 970 on our mission list?
Hammond: It was. Not anymore. I'm not taking any chances. I want P4C-970 removed from the dialing computer immediately. Dismissed.
Carter: I wonder why you sent it. I wonder when.
O'Neill: Yeah. Gotta wonder.
- The title of this episode is a homage to Arthur C. Clarke's novel Plantilla:WPS. The "Jupiter ignition project" is also an homage as Jupiter is converted into a second sun at the end of the novel. Coincidentally, Arthur C. Clarke's Space Odyssey series used the term "StarGate" to refer to one of its major plot devices, the monolith. This episode is also the first part of a short story arc continued in the episode "2001", the title of which is a homage to Clarke's novel 2001: A Space Odyssey.
- The story of this episode is followed up in the Season Five episode "2001", in which the SGC makes contact with the Aschen, through encountering them on a different planet.
- This episode is one of only three to feature Teal'c without his golden Apophis tattoo. The other episodes are The Gamekeeper" and "The Changeling".
- Colonel Jack O'Neill's reference to the lack of fish in his pond is also featured in "The Curse", "Threads", "Moebius, Part 2" and "200".
- This episode establishes MSgt. Harriman's first name as Walter, due to an ad lib of Richard Dean Anderson's. The name is a reference to Plantilla:WPS from the series Plantilla:WPS.
- In the Gateroom at the SGC museum, curiously, a banner is displayed which bears the logo of the Bedrosian forces.
- In the tour scene a tourist has his picture taken in front of the replica Stargate while doing the Vulcan salute from Star Trek.
- It is said in the episode that Major General George S. Hammond died of a heart attack in 2004. The actor, Don S. Davis, actually died in 2008 of the same cause. Because of this, his character was also revealed to have had a heart attack in the same year. This was referenced in the final episode of Stargate: Atlantis, "Enemy at the Gate".
- At 17:35 Jack O'Neill says to Carter, "I'm retired Carter, lose the 'sir'." This is a reference to "Children of the Gods" in which he told Major Kawalsky, "I'm retired Kawalsky, lose the salute."
- The events of this episode begin on July 27, 2010, which is erroneously indicated to be a Thursday on Joseph Faxon's newspaper. In actuality, it is a Tuesday.
- Colonel Jack O'Neill talks about the peace of not having to save the world and having a pond with no pesky fish. Looking closely at the end of the scene, a carp can be seen swimming in the pond at the surface gulping air. However, the comment was most likely meant to be sarcastic, as most of Colonel Jack O'Neill's comments are.