Rodney McKay is reunited with his estranged sister back on Earth, who has given up a brilliant career as a scientist to raise a family.

Dr. Rodney McKay is infected with the Pegasus equivalent of Alzheimer's disease, known as Second Childhood, a common illness among the elderly in the galaxy. The only way to save him is a shrine on Talus. The downside is that it has turned into a Wraith outpost.