Unnatural Selection

"Unnatural Selection" in the twelfth episode of the sixth season of Stargate SG-1.

Plot
Thor, who has rescued SG-1, informs them that he needs their help to defeat the Replicators and because the Prometheus isn't very advanced (compared to Asgard standards), they could fly unchallenged into Replicator-controlled territory. In addition, he informs them that the Asgard were able to call all Replicators back to one point, their first colony world, Hala, by using a signal found in the android Reese. They then tried trapping them using a time-dilation device, in a sphere encompassing the entire planet, but their plan ultimately failed. If they are allowed to escape, they will conquer the Asgard and most likely be drawn to the Milky Way and Earth's raw materials. Now he wants SG-1 to solve this problem but Col. O'Neill is by no means interested in this operation. Thor brings them back to Earth, where he beams up supplies from the SGC and transports extraneous passengers off the Prometheus (left on board after the episode "Prometheus"), except SG-1, to the planet.

Jack later uses a holographic communicator to contact General Hammond and briefs him about the situation. Afterward, he talks with Major Carter about the Asgard plan and then goes to the cargo bay to eat something, where he meets Jonas and Teal'c. They talk about the Replicator threat then feel themselves losing speed. Thor tells them that they have reached their target but the time-dilation device has long since been changed so that time now passes faster within the field ("by a factor of ten squared," as Thor explains). Thor wishes them luck and departs.

SG-1 flies near Hala, is scanned by a Replicator ship, and enters the atmosphere of the planet. They land on a large surface with only one construction, the one spot on the planet that breaks the smooth terrain. As SG-1 steps outside, it turns out that the whole ground consists of Replicator blocks. They enter the nearby building and find the time-dilation device, when suddenly a man appears. Then, four more human-like persons appear and an older man demands that Carter stop her work on the device. The groups reveals that they are in fact replicators. Upon hearing this, SG-1 opens fire on them—–with no success. Suddenly, several bug-like replicators appear and surround the team, so they are forced to disarm. The leader of the five human-form replicators offers O'Neill his hand but when O'Neill takes it, the man seemingly pushes his hand into O'Neill's head and Jack finds himself in the Gate room where the man appears. The replicator tells him that they are in O'Neill's unconscious mind. Eerily, the replicator starts to read O'Neill’s mind, including his iris deactivation code. The two go through an imaginary Stargate.

SG-1 wakes up, finding themselves back on the Prometheus. It turns out they have all experienced the same thing. In order to decimate this new threat, they plan to blow up the hyperspace engines. However, when they go to execute this plan, they meet one of the human-form replicators, who calls himself Fifth. He tells them that they are invited for meal with the other human-form replicators. SG-1 quickly returns to the building and First tells them about their history and construction. First explains that, instead of the larger replicator blocks, they consist of microscopic cell units. First also tells them that it was he who deactivated the time-dilation device and reprogrammed it. They converse about Reese and the error that embedded in her systems (previously encountered in the episode "Menace"). First, with a condescending attitude about him, reveals that they attempted to correct the error in Fifth, yet First says Fifth is weak. Fifth is ordered to enter one of their minds and Carter agrees to. However, they enter Fifth's unconscious mind and develop a plan to repair the time-dilation device.

SG-1 awakens again with Fifth telling them that he has reconfigured the device. While Jonas and Teal'c return to the ship, Carter programs the device. However, she is secretly ordered by O'Neill to set the time on three minutes instead of the predetermined five, which they originally told Fifth to be the setting. SG-1 starts toward the ship after telling Fifth to head there himself shortly after three minutes. First suddenly appears and tells Fifth that SG-1 has lied to him but Fifth is adamant in his convictions about SG-1’s honorability. He looks at the timer and is shocked to find that it’s nearly to zero. Just as it activates, SG-1 leaves the planet. However, both Jonas and Carter feel badly that they used Fifth's "humanity against him."

Notable Quotes
O'Neill: Suffice to say, you might want to get upstairs and punch one on the old speed dial.

Hammond: My grandchildren?

O'Neill: Two, then.

Carter: So what didn't they go for?

O'Neill: The name I suggested.

Carter: For the ship?

O'Neill: Yeah.

Carter: Yeah. Sir, we can't call it the Enterprise.

O'Neill: Why not?

Thor: If you wish to reconsider-

O'Neill: No, no. I full well expected the other shoe to drop eventually.

Thor: We can only hope that this will be the last footwear to fall.

O'Neill: What is with you people? Time machines are nothing but trouble. Even we know that!

First: Your mind is incredible.

O'Neill: Well....

First: Such chaos and humor and pain.