Lifeline

"Lifeline" is the second episode of the fourth season of Stargate Atlantis.

Synopsis
John Sheppard and his team use Elizabeth Weir to perform a daring operation to infiltrate the Replicator homeworld, to steal a much needed ZPM to power Atlantis and go to their new home. In the same time, the Apollo continues to search for the lost city.

Previously on Stargate Atlantis
Atlantis attempted to flee Lantea from the beam of the Asuran Stargate satellite. However, the city was grazed by the beam and exited hyperspace early, and ended up drifting in space with little power left. The Expedition worked to restore the stardrive, but had to survive an asteroid belt. Meanwhile, Jennifer Keller tried to save Weir, but in the end, had to resort to Rodney McKay reactivating the nanites in Weir's cells, against Sheppard's orders not to. Despite attempting to restore the hyperdrive, the city's power levels dropped below the minimal power requirements to require a jump. However, with the plan to implement a hyperdrive on a Puddle Jumper, they realised the Replicator homeworld was nearby, and planned to steal a ZPM from there.

Plot
In the still-drifting Atlantis, Rodney McKay and Radek Zelenka are in a Puddle Jumper, completing the calculations to implement the hyperdrive. After a mishap, invlolving a short circuit, John Sheppard arrives, checking up on the progress. However, he tells McKay a problematic question, that even if they did arrive to Asuras and steal the ZPM, escaping would be suicide. McKay says he had been thinking, and decided that if they stand any chance to succeed, they need help. They turn to the seemingly recovered and improved Elizabeth Weir. They ask for her help.

McKay tells Weir with the team that with her nanites, they will be able to use them to their advantage to steal the ZPM. They could use them to get in and out without being noticed. However, if the Replicators are able to take control of her, Sheppard will order McKay to activate the kill-switch, which will terminate the nanites, but since the nanites are the only thing keeping her alive, she will die. Despite the big danger, Weir immediately wants to start the mission. Sheppard talks with her alone. Weir tells him not to hesitate with the kill-switch, despite his assurances that it will not happen.

McKay finishes up on the hyperdrives. Ronon Dex comes in and tells Sheppard that they're ready, despite McKay's scepticism that they could break up on entering hyperspace. Meanwhile, Sheppard tells Teyla Emmagan to stay behind. He tells her that Zelenka found a planet for the city to jump to, but that they would have to evacuate, since the power would be too drained to achieve a stable orbit. He tells her that if he and his team don't return within twelve hours, she should give the order to jump. He then proceeds to the Jumper, where the team takes off. Sheppard tells those remaining on Atlantis not to get into any "wild parties" when they're gone. The Jumper then successfully jumps into hyperspace.

Meanwhile, Colonel Samantha Carter and Doctor Bill Lee arrive on a beautiful planet in the Pegasus galaxy. Lee comments that the planet looks a lot like Elwynn Forest from World of Warcraft. He takes out a camera to take a picture. However, Carter contacts the Apollo, who quickly beams them both onboard before Lee takes the photo. Carter tells Abe Ellis the plan to find Atlantis. It is a simple, yet tedious one. Assuming that Atlantis dropped out of hyperspace early, they would have to power up the Apollo's sensors to extend their range significantly. They would follow Atlantis' original path, making a short hyperspace jump, scanning the area, and then jumping to the next area. Naturally, such a process is incredibly time consuming, as it would require about 50 jumps.

The Jumper successfully drops out of hyperspace and cloaks over the Replicator homeworld. However, too much power was used, so they can't jump back. McKay then proposes to use the to-be-acquired ZPM to power the ship. McKay then tweaks with the nanites, while Weir finds her way into the collective, where she is easily able to find an unguarded ZPM. The cloaked Jumper lands above the building, where Sheppard and Ronon exit and follow Weir's instructions. They easily enter to steal a ZPM. They then manage to return to the Jumper undetected. However, McKay discovers the command directive to attack the Wraith that was left dormant, and proposes to use Weir to reactivate it. However, Sheppard doesn't want to hear about it and prepares to leave the planet. McKay then has another proposal; they can upload his code to activate it through the Central data core so the Asurans will start to attack the Wraith on the next merge. The problem is that it is in the middle of the building in the centre of the city. Sheppard decides to do this after they return from Atlantis. However, if they leave now the Asurans will upgrade their security and the team will not have this opportunity again.

The Apollo exits its eleventh hyperspace jump, with 39 to go. However, the long range sensors aren't able to pick up Atlantis, meaning they still haven't found them. They prepare jump number twelve.

The Jumper arrives over the necessary building, where they de-cloak to make room for an Anti-Replicator field, which will protect the core room and the Jumper. Sheppard leaves McKay with Weir, while he and Ronon make their way to the core room. However, Oberoth is made aware of the field, and finds out that the core is inside it. He orders the other Replicators to attempt to breach the field. Meanwhile, Sheppard plugs the computer tablet with McKay's code into the core, but nothing happens. With several Replicators scarificing themselves to override the field's frequency, McKay quickly instructs Sheppard on implementing adjustments to the negotiation protocol to exploit parallelism at the device interface. However, the Replicators are quickly able to breach the field, and Oberoth is on his way.

With no other alternative, Sheppard frantically works on fixing the interface before getting captured. When Weir suddenly leaves McKay, he attempts to disable the nanites and kill her, ignorant of her true intention (to stop Oberoth), but the command fails to work for unknown reasons. Meanwhile, Weir confronts Oberoth and makes physical contact with him, connecting herself to the Replicator network. She uses her access to freeze all of the Replicators, giving her team time to allow them to escape. A surprised Oberoth admits that he admires her attempt, but is quickly able to overpower her, claiming to her that she has under-estimated him. Now that he has regained control, all the Replicators start moving again. They easily capture McKay, Sheppard and Ronon trying to escape.

With all of them captured, Oberoth visits them in a holding cell, telling them that Weir's attempts to stop him proved too taxing for her, and is going to upgrade her to join the collective. He then wants to probe their minds on the precise location of Atlantis, so the Asurans could destroy it. However, Oberoth finds it hard to extract the information. He then discovers that it was all a trick, made by Weir. In reality, all the Replicators are still frozen. Weir says that she never under-estimated him, but he has truly under-estimated her. Oberoth angrily tells her that she will not leave the city alive, which Weir replies by saying that her team will.

After fixing the interface, and uploading the Wraith attack code, Sheppard is ready to go back to the Jumper, but not before getting Weir back. Oberoth, who will not be fooled again, overpowers Weir for real this time and manages to physically grab her arm. Sheppard and Ronon find her, and even try to shoot Oberoth with an Anti-Replicator Gun, but can't terminate him, since the Replicators have managed to override the frequency. Weir, who can't release herself from Oberoth, pleads with Sheppard to leave her behind, and is eventually forced to order him to do so, as the Replicators regain control and fire at them, and surround Weir, preventing her escape. Sheppard is forced to leave her behind and run back to the Jumper and escape without her.

Unfortunately, escaping the planet is far from easy, since the Jumper has exhausted too much power to cloak and jump away. McKay quickly attempts to install the ZPM to power the ship again, but they're being pursued. The chasing ships manage to disable the Jumper's weapons. The jumper leaves the planet's atmosphere, only to find a patrol ship de-cloaking in front of it. Just as the team braces for its fate, however, the Asuran ship is mysteriously attacked from its port side. The attackers identify themselves, it is the Apollo.

They Apollo had managed to find Atlantis, who told Ellis about where Sheppard's team went. Ellis clears them for entry into the flight deck. They try to beam over Weir, but can't find her subcutaeneous transmitter anywhere. The Jumper arrives in the Apollo, which then jumps away.

Back in Atlantis, they are able to install the ZPM, and the city is now fully powered. McKay finds them a new home planet, M35-117, a planet with a large ocean, like Lantea. He purposely left out a group of planets during earlier considerations, so the Asurans can probe Weir's mind and still never find Atlantis. The city jumps into hyperspace, and arrives over M35-117. Sheppard goes into the Control chair, where he will land the city. The re-entry into the atmosphere and landing are very rough, but the city is now on its new ocean, with plenty of power remaining in the new ZPM.

At night, a grieving Ronon and Teyla pack away Weir's personal belongings, wondering who will fill in for her. Meanwhile, Carter and McKay are able to contact Stargate Command and are now back on the grid. Also, Zelenka arrives with a surprising announcement; long range scanners have detected a massive fleet of Asuran ships heading for a Wraith controlled planet. McKay concludes that their mission was indeed successful. Later, Carter talks with Sheppard, looking over the two visible moons on their new planet. Carter tells Sheppard that she is amazed that they have pulled off the mission. She has been ordered back to Earth, and passes on General Hank Landry's condolences for the loss of Weir. Sheppard, however, vows that he will find her again.

Notable quotes
After McKay has a close call with a power surge. Sheppard: How's it coming? McKay: (Pointing to Zelenka) Well, we'd be making a lot more progress if "Timmy Torture" here wasn't trying to kill me every two seconds. Zelenka: I'm not trying to kill him.

After arrving on the Asuran homeworld by Jumper Hyperdrive McKay: Believe it or not, Zelanka was right. McKay babbles on about the hyperdrive being burned down Sheppard: So what are you trying to say? We can't go back? McKay: No, what I'm trying to... Actually that is exactly what I'm saying.

Sheppard: Have we got enough energy to keep the shield up for re-entry? McKay: There’d better be. What, a city this size'll create considerable friction. We come in too fast or too steep and the shield could attenuate under the stress and the whole place'll be torn to shreds, or burn up, or both. Sheppard: It never ends with you, you know?! McKay: What?

McKay: We wanna touch down gently, like a leaf kissing the surface of a pond. (The shaking city makes a very rough landing over the ocean) Nice kissing!

(The team braces for death when suddenly the Asuran Warship is hit by missiles, surprising the team) Sheppard: What the hell was that?! (The Apollo is revealed to be attacking the Asuran ship) Ellis: Colonel Sheppard this is the Apollo, do you read? Sheppard: (shocked by this) Colonel Ellis is that you? Ellis: Affrmative, the 302 bay is open and you have permission to come aboard, I suggest you hurry. Sheppard: Copy that Apollo. We're on our way. McKay: Can I add that your timing is pretty damaned perfect?! Carter: We would have gotten here earlier but we had a little trouble finding Atlantis. McKay: (surprised) Sam, is that you? Carter: It's me Rodney, I'll explain when you get onboard. Sheppard: Colonel we lost Doctor Weir on the Replicator planet. Can you lock on her locator becaon and beam her up? (Carter tries but fails) Carter: (sadly) I'm not picking up any signal. (The team is visibly sadenend) Sheppard: (sadly) Copy that. (The Jumper lands on the Apollo which continues to lay down covering fire then jumps to hyperspace once the Jumper is aboard)

Background notes

 * Teyla Emmagan announces the "Previously on Stargate Atlantis" in the beginning of the episode.
 * Clearly in the "previously on Stargate Atlantis" McKay can be seen with many cuts on his face, yet very soon after it appears as if they are all healed. In fact, there is absolutely no indication that they were ever there at all.
 * Atlantis Expedition country members seen: Canada, New Zealand, United States.
 * After a planet suffers several nuclear strikes, its atmosphere's colour would turn from blue to yellow for several years or even decades. However, "Lifeline" was set only about a day after "First Strike" and the atmosphere of Asuras was still blue. It is possible that the Asurans, being incredibly technologically advanced, could have devised a way to quickly clean the atmosphere.

Production

 * On September 12, 2007, unfinished versions of this episode and "Adrift" were leaked onto the internet.
 * Executive producer Joseph Mallozzi has stated that "Lifeline" is a "big op eppy".