Season Two
A young boy comes through the Stargate looking for his mother. The boy was made in human form to interact with humans, his mother is a Reetou, who are invisible. The Goa'uld destroyed their home planet and now a group of rebel Reetou want to destroy all potential hosts, including the Tau'ri.
The SGC call on Jacob to help them, he brings with him a piece of Goa'uld technology a TER, (Transphase Eradication Rod) which can make the creatures visible. But it could already be too late, there is no way to determine how many of the creatures may already be on the base.
Meanwhile the boy who has been named Charlie after O'Neill's son is dying, due his accelerated growth his organs are failing, maybe the Tok'Ra can help him too.