Master Bra'tac sends an emergency signal through the gate, and on arriving on Earth, tells Teal'c that his son Ry'ac has been taken prisoner by Apophis. The team are slightly taken aback - they thought they'd taken care of Apophis and Klorel when they blew the ships up in orbit. Apparently, though, they managed to escape (the audience saw the two of the use the rings before the ships exploded), and Apophis has set up on Chulak again, albeit much weaker, and vulnerable to attack from another system lord.
Realising that Ry'ac's kidnapping is a trap to catch Teal'c, they go to Chulak anyway to mount a rescue mission. Teal'c learns that his wife Drey'auc has remarried an old friend of his, Fro'tak (who, unfortunately, doesn't sport a 'fro), and isn't too happy about it. The first rescue attempt fails when Ry'ac is shown to have been brainwashed by Apophis, but he leaves Teal'c a hidden message asking to be freed once he has apparently broken through the brainwashing.
After killing Fro'tak when he turned informer, they follow Ry'ac's clue and bring him safely back to Earth, but he was just one of Apophis' pawns - he had false teeth with poison inside, designed to wipe out all life on Earth. The teeth are removed, though, and all that's left is to deprogram him, ultimately through a zat'nik'tel blast.
The episode features some really great acting from Neil Denis, playing Ry'ac. He was only 10 or 11 years old at the time, but did an excellent job of playing someone playing a role, when Ry'ac is still under the influence of Apophis' brainwashing but trying not to let on. The moment he spits on his father's face is really powerful, and Christopher Judge is fantastic as a concerned father, too.
It's also always a pleasure to see Tony Amendola as master Bra'tac. He always declines returning to Earth, though, and I have to wonder what there is for him on Chulak? I guess he's trying to stir up more rebellious jaffa, especially now that Apophis is hugely weakened, but it's got to be a dangerous game. He no longer needs to look after Drey'auc and Ry'ac, either, as they have moved to the Land of Light (from the season 1 episode The Broca Divide).