Richard Dean Anderson (“Jack O’Neill”) will guest star in Stargate Atlantis‘s mid-season 2-parter, GateWorld has learned. The first details have arrived for the plot of “The Return,” written by Martin Gero. Part two of the story will be directed by Brad Turner.The episode will also guest star Robert Picardo as Richard Woolsey.Beware of spoilers for this and previous Atlantis Season Three episodes below, including “Progeny.” As specific details are only available for “The Return, Part 2,” watch out for spoilers for this and part one as well.The Asurans, a race of powerful artificial lifeforms who were created by the Ancients thousands of years ago and who the Atlantis team first met in Season Three’s “Progeny,” have conquered Atlantis. The Asurans are made up of trillions of microscopic nanites, and their abilities lead the team to believe that they are the original technology on which the human-form Replicators were later based (SG-1: “Unnatural Selection”).To help fight their new enemy, the Atlantis team calls in one person most up to the task: Major General Jack O’Neill, who has dealt with the Replicators in our galaxy many times. But when the Asurans take control of the city of Atlantis, O’Neill and Richard Woolsey find themselves captives.Sheppard, Weir, McKay, and the rest of the team attempt to come up with a rescue plan. Part of their plan is to reprogram Niam, an Asuran replicant who was sympathetic to the team at their last encounter. McKay, of course, thinks he’s up to the job.After an attack by the team leaves the control room in shambles, the Replicators work to get the systems back online. Two Replicators, Talus and Cetus, arrive at the holding cell where O’Neill and Woolsey are being kept. The two are forced to their knees for interrogation, as the Replicators plunge their hands into O’Neill and Woolsey’s foreheads to probe their minds.Guest characters include Jack O’Neill, Richard Woolsey, Niam, Talus, and Cetus.Executive producer Brad Wright recently said in an interview that Anderson’s return to Stargate this year will include two appearances on SG-1 and three on Atlantis. Based on what we know so far, this includes Atlantis‘s “The Real World,” “The Return, Part 1,” and “The Return, Part 2”, and Stargate SG-1‘s “200.” The second SG-1 episode has yet to be revealed.It is likely, though not yet confirmed, that part one of “The Return” will air as the mid-season cliffhanger in September, followed by part two in January. Part two will go before cameras in Vancouver next week.Learn more about the year ahead in GateWorld’s Season Three episode guide!