Beachhead

"Beachhead" is the sixth episode of the ninth season of Stargate SG-1.

Synopsis
The Ori plan to use Kallana, a Jaffa stronghold, to stage an invasion of the Milky Way. SG-1, with the help of Lt. Colonel Samantha Carter, send the Prometheus to stop it.

Previously on Stargate SG-1
Lt. Colonel Cameron Mitchell asks Lt. Colonel Samantha Carter to rejoin SG-1 but she declines but promises to help if the world needs saving. Vala Mal Doran uses Kor mak bracelets to link herself with Dr. Daniel Jackson. A Prior visits Stargate Command and sets himself on fire.

Plot
When Nerus, a minor Goa'uld and hedonist, requests an alliance with Earth, Major General Henry Landry and SG-1 don't need Vala Mal Doran to warn them that Nerus can't be trusted. Vala warns them anyway, but Landry decides to risk inviting Nerus to Stargate Command.

Nerus explains that a mysterious force field has appeared on the planet Kallana. The field surrounds Kallana's Stargate and periodically increases in size. Worse, the Stargate hasn't shut down for two days, which violates all known laws of physics. Worst of all, there's a Prior of the Ori on the scene. The team is forced to agree with Nerus's frightening conclusion: The Ori must be establishing a beachhead from which to launch their invasion of our galaxy.

Landry orders Lt. Colonel Cameron Mitchell and SG-1 to use any means necessary to stop the Ori. To that end, he sends along the military's latest superweapon, the Mark IX "Gatebuster" Naquadria-enhanced Nuclear warhead. He also sends the Mark IX's designer: Lt. Colonel Samantha Carter. SG-1's pleasure at working together again is tarnished only slightly by Vala tagging along. Her life is still linked to Dr. Daniel Jackson's, but now, in the presence of the full SG-1 team, even she can tell that she's just a fifth wheel.

SG-1 travels aboard the Prometheus to Kallana, where the force field has grown so large that it's visible from orbit. Mitchell, Daniel, Teal'c, and Vala manage to transport down to the planet's surface with the Mark IX. They try to negotiate with the Prior, threatening to use the Mark IX in 30 “earth minutes”, but even the threat of imminent nuclear vaporization doesn't budge him.

Suddenly, a bombardment of energy weapons rains down from above. Gerak, the leader of the Free Jaffa Nation, has learned of the Ori incursion and demands to take matters into his own hands. At the same time, the force field expands again. Out of options, Mitchell arms the bomb and transports his team back to Prometheus.

Humans and Jaffa alike brace for impact as the Mark IX detonates below. As the shockwave dissipates, they are stunned to discover that the force field has only gotten bigger. Soon it will engulf the entire planet, and they have no idea what will happen next. Gerak resolves to continue his bombardment of the surface, threatening to target the Prometheus once he has dispatched the Ori if the Tau'ri do not join him in his attack.

Mitchell gives the order to attack. Before long, Carter notes that their attacks are only making the force field bigger: The force field is using their attacks to power and increase itself, and as Nerus, who reveals he has been working with the Ori all along, informs Landry, the Ori would have been unable to get this far without Earth's Mark IX. The Tau'ri plan has backfired.

Once the force field has engulfed the entire planet, a number of small, rectangular projectiles eject from the Stargate, destroying two of Gerak's ships. Meanwhile, the force field begins to collapse the entire planet into a micro-singularity. Gerak retreats as the projectiles come together, forming a colossal ring in planetary orbit. SG-1 gapes in awe as the first Supergate forms before their eyes. The Supergate, between 300 and 400 meters in radius, powered by a black hole, is large enough to allow an Ori armada to enter the Milky Way galaxy.

Carter notices that the pieces of the Supergate are becoming interconnected by a common energy signature. Vala, who realizes that Gerak has left behind a cloaked Tel'tak to watch them, uses the Transportation rings to board the ship. She moves the ship into the path of the last piece of the Supergate, disrupting its energy signature. When the planet finally collapses and the micro-singularity forms, the shockwave destroys the Tel'tak and disperses the now-inert pieces of the Supergate. The Ori beachhead is thus destroyed, and Nerus is sent to a prison underground in Area 51 until he comes up with a plan to fight the Ori. Nerus asks, "What would possibly compel me to do that?" Landry answers, "Hunger."

Vala vanishes after the explosion, which puts Daniel in danger, but SG-1 soon realizes that the effect of the bracelets has begun to wear off. Carter notices that a matter stream left the cargo ship before it exploded. Vala may still be alive somewhere in the Ori galaxy. Daniel breathes a sigh of relief, saying, "Well, we wanted to send them a message."

Notable Quotes
Vala: You boys aren't gonna let people from two different planets beat you at your own silly game are you?

Jackson: This silly game isn't over yet.

Mitchell: That's my wingman.

Vala: You need a new wingman.

Jackson: I'm gonna kick your ass.

Vala: Promises promises.

Mitchell: Lt. Colonel Cameron Mitchell. Leader of SG-1.

Nerus: But you’re not...

Mitchell: No.

Nerus: Will he be here?

Mitchell: Nope.

Nerus: (to Vala) And you're not even Colonel Carter, are you? This isn't at all the way I imagined it.

Mitchell: Oh boy, and here I was trying to have a nuke-free career.

Jackson: Vala, this is a military vessel.

Vala: I know darling, I've stolen it before.

Jackson: Just try to be...

Vala: My charming self?

Jackson: Just a little less talk, a little more shut the hell up.

Vala: My god, it's enormous!

(Jackson gives her a disapproving look)

Vala: Not everything I say is innuendo.

Carter: A matter stream left the cargo ship just before it exploded. There's at least a slight chance that it was pulled into the singularity.

Jackson: So you're saying she could be alive somewhere in the Ori galaxy?

Carter: It's possible.

Jackson: Well. We wanted to send them a message.

Goofs

 * When the Jaffa are firing on the forcefield one of them is clearly an M16 variant assault rifle. It is unsure if this is a mistake or if the Jaffa have been given human weapons as part of their alliance.
 * When the Supergate components approach the Prometheus, Colonel Lionel Pendergast orders emergency thrust, yet in the following special effects shots the thrusters are inactive and the ship is not moving.

Nominations

 * Nominated Gemini for "Best Visual Effects" (Mark Savela, Vinay Mehta, Brendon Morfitt, Anuj Patil, James Rorick, Craig Van Den Biggelaar, Karen Watson and Kyle Winkelman)

Character

 * Nerus

In other languages

 * French: Le Piège (The Trap)
 * Italian: La Trappola (The Trap)
 * Spanish: Cabeza de Playa (Beachhead)
 * Czech: Předsunutá základna (Beachhead)
 * German (DVD/TV): Das Schutzschild (The Shield) / Der Brückenkopf (The Beachhead)