“New Order: Part 2” is episode two of season eight of Stargate SG-1.
In the previous episode, “New Order: Part 1”, the Asgard had tried to destroy the Replicators by turning the sun of the planet they were on into a black hole. This had failed, and a Replicator ship had escaped, captured Major Carter, and headed to the new Asgard homeworld. Where it was apparently destroyed. I doubt that they managed to actually destroy the Replicators though.
The Goa’uld System Lords had requested Earth’s help, using the new super weapon discovered in “Lost City: Part 2” that had been used to destroy Anubis’s fleet, against Ba’al. Dr Weir had tried to stonewall them, because they weren’t even sure they would be able to fire the weapon again, but the Goa’uld had sent out a message telling the others to attack Earth.
It turns out that, although the Replicator ship had been destroyed, the Replicator blocks landed on the planet and are taking over the planet. The Asgard are unable to flee, or they will lose many stored consciousnesses. Odd how an empire is now reduced to one planet. The Asgard want the Ancient knowledge from O’Neill’s mind, as they think it will be able to save them
Sam wasn’t killed when the Replicator ship was destroyed, but she’s now in some sort of presumably virtual environment.
The Ancients are shown as being rather more competent than they will be in Stargate: Atlantis.