When the Thompsons have a change of heart about going to the Millers' cabin, Susan asks the Deckers to join them. The weekend gets off to good start but then the Thompsons decide to surprise them by showing up anyway.
The team learns of an ancient weapons system in the village of Camelot on an alien planet.
Using an Ancient communication device, Vala contacts the SGC through Daniel and informs them of what's been happening in the Ori's galaxy.
Carter and Mitchell find themselves trapped on another plane, out of phase and invisible to everyone else. While Sam attempts to reverse the procedure, Mitchell goes after an assassin who is wiping out the Sodan.
While a group of foreign delegates are touring the Gamma Site, a swarm of alien bugs linked to the Ori escapes containment...and adapt to become carnivorous.
The SGC learns that the organization of traders and mercenaries known as the Lucian Alliance is distributing a highly-addictive drug and SG-1 goes to investigate. But the situation becomes complicated when the planet's Stargate disappears...and SG-1 is held responsible.
SG-1 and the Prometheus travel to Tegalus to stop the Rand Protectorate from using an Ori-supplied superweapon to destroy their enemies, the Caledonians. But things turn grim when Daniel is captured and the Prometheus is caught in a firefight
Ba'al kidnaps and brainwashes members of the Jaffa High Council in a bid to seize control of the Jaffa. Meanwhile, Mitchell debates whether to reveal the Stargate program to a dying friend who was once in line for his SG-1 position.
Alternate realities coming together at Stargate Command create alternate versions of SG-1 and some of their fallen allies.
When SG-1 travels to an Asgard protected planet, Colonel Mitchell is accused of a murder he did not commit...but has memories showing he did.