Stargate Atlantis/Recap/S01/E06 Childhoods End

"Ford: Have you kids ever heard of chocolate?

Casta and Cleo: (headshake)

Ford: Well then, this is gonna be HUGE."

Sheppard and his team are grounded on an alien planet after their Puddle Jumper is knocked out of the sky by some sort of energy field. They trace the EM disturbance (by its effect on a magnetic compass, since nothing else works) to some ancient ruins, where they are immediately ambushed by a group of children in warpaint. The war band takes them back to their village, where again only children are in evidence. The locals are shocked at the presence of "full-growns" and turn the problem over to the village "elders."

The elders all turn out to be 24, still younger than any member of the team (Ford turns out to be 25). The eldest of those, Keras, is the leader, with final say over everything. He explains that their planet has not been visited by the Wraith for 500 years, which is especially good because their religion depends on peaceful death (rather than being eaten alive) in order to gain access to the afterlife. The way the Wraith have been kept away is by the villagers deliberately denying them "a crop worth harvesting" - by ritually killing themselves on the eve of their 25th birthdays. This peaceful death ensures them a place in the afterlife and protects the entire community from the threat of the Wraith.

Naturally, Sheppard is horrified. He is distracted, however, by a radio call from McKay, who has found and deactivated the energy shield. What's more, said shield was powered by a ZPM, which the team has been desperately seeking in order to power Atlantis' own shields. McKay wants to take it back to Atlantis to see if they'll be able to use it, although Sheppard expresses concern at depriving the villagers of their only means of defense. But, really, what's the chance the Wraith will turn up in the hour or two it takes to run some tests and get back?

As it turns out, pretty much 100%, since the moment the shield went offline a Wraith bracelet on a handy pile of bones started transmitting a homing signal. To make matters worse, Keras' second in command Aries is increasingly convinced that the mere presence of people over 25 in the village will bring the Wraith back upon them. The only safe option is to subject them to "involuntary sacrifice." Still worse, tomorrow is Keras' birthday, so his own sacrifice is scheduled for tonight.

Back on the base, McKay discovers that the ZPM is close to being depleted anyway, and is therefore not of much use to Atlantis (although should protect the villages for some time to come). He also figures out that the reason for the suicide pact is a form of population control - to prevent the villagers from straying outside the limited area protected by the energy shield. Dr. Weir manages to convince him to give back the stolen ZPM, despite his objections that the kids would probably be fine, and if not, they could just move them to Atlantis, or even the continent.

Just in time too, as a Wraith probe has been seen around the village. Sheppard and team promise to leave immediately, but instead head to the shield device, which McKay has somehow managed to break. Aries takes this as final proof of their treachery and danger to the villages, and readies to proceed with the involuntary sacrifice. At the last possible moment, McKay manages to get the ZPM configured correctly, and the warriors see the Wraith probe plummet out of the sky. The team is allowed to depart peacefully, after distributing gifts of chocolate, and the locals can now stop killing themselves and look forward to the prospect of grandchildren.

Tropes
"Sheppard: Please tell me you have this working. McKay: I don't know what I did. These things are usually plug-and-play. This device must be using an older version of Windows."
 * Buffy-Speak: "Energy field Good."
 * Call Back: McKay reminisces about helping Samantha Carter avert global catastrophe in the SG-1 episode "Redemption".
 * Child-Hater: McKay, played for laughs - so naturally all children love him.
 * Literary Allusion Title: to Arthur C. Clarke's Childhood's End, although the plots are unrelated.
 * Kinetic Weapons Are Just Better: The energy field that knocks out the Puddlejumper has no effect on primitive firearms.
 * Nice Job Breaking It, Hero
 * Rock Beats Laser: The real reason the Wraith haven't bothered attacking this planet in 500 years.
 * Suicide Pact: An unconventional example, in that it wasn't all at the same (absolute) time, but at a prearranged date in the lifetime of each individual.
 * Take That:

"Weir: Rodney! We can't just visit planets, take away their defenses, uproot their cultures and bring ‘em all back here to Atlantis. McKay: If they have a ZedP.M., yes we can. Weir: Oh my God! How morally superior you must feel!"
 * Tastes Like Friendship: see page quote.
 * Teenage Wasteland: Type 2
 * Tracking Device: The Wraith bracelet
 * What the Hell, Hero?: Weir to McKay, when he suggests stealing the kids' ZPM.