Today GateWorld has brand new story details for “First Contact” and “The Lost Tribe,” the highly anticipated two-parter airing in just one month! The episodes guest star Michael Shanks as SG-1’s Dr. Daniel Jackson.

“First Contact” premieres in the U.S. on Friday, September 26. Stargate Atlantis will then take a break for just one week, with “The Lost Tribe” airing on October 10.

Here is how the SCI FI Channel describes these episodes:

FIRST CONTACT
“Stargate SG-1‘s Dr. Daniel Jackson travels to Atlantis when his research suggests that a rebellious Ancient scientist named Janus may have hidden a secret lab somewhere within the city. Hoping to find it, and possibly a significant portion of his unauthorized research, Jackson enlists Dr. McKay’s help. An obscure log entry leads them to a cloaked lab where they unwittingly activate a signal on a distant planet. Hours later, the city is paid a visit by a group of mysterious aliens.

“Meanwhile Woolsey, along with Dr. Keller and Ronon, have joined Colonel Caldwell on board the Daedalus, leaving Sheppard in charge of Atlantis. They welcome Todd and his delegation to the ship to discuss testing Keller’s gene therapy on live Wraith subjects. But events take a turn for the worse when Todd, suspecting them of betrayal, takes control of the Daedalus.”

THE LOST TRIBE
“Dr. Daniel Jackson and Dr. Rodney McKay have been forced to reactivate the Attero device, a machine designed thousands of years ago to annihilate the Wraith. In doing so, they discover the reason the device was ultimately abandoned by its Ancient creator — while destroying Wraith ships that attempt to travel through hyperspace, the weapon inadvertently causes active Stargates to self-destruct.

“Meanwhile, Todd and his troops continue to hold Woolsey, Keller, Ronon and the Daedalus crew captive, convinced that they are behind the resurrection of this deadly technology. Fearing that if Todd succeeds in destroying the device, Jackson and McKay will most certainly be killed in the process, Sheppard calls on some old allies to help him rescue his friends.”

Tune in to new episodes of Stargate Atlantis every Friday in September, at 10 p.m. (9 Central) on SCI FI. Learn more about these and other upcoming episodes in GateWorld’s episode guide!