Young Jack: Michael Welch
Dr. Janet Fraiser: Teryl Rothery
Jacob Carter: Carmen Argenziano
Sam is called in to speak with an intruder trying to enter the SGC with Jack's security pass. It turns out that the intruder is a teenage boy who claims to be Jack O'Neill. Although SG-1 and Hammond are skeptical, the boy knows everything Jack would know. When it turns out that his DNA almost perfectly matches that of O'Neill's, SG-1 concludes that the young man is indeed Jack O'Neill, only mini-sized. They set out to determine how and why and if it can be reversed.