“The Serpent’s Venom” is episode fourteen of season four of Stargate SG-1.
Teal’c is visiting Chulak, trying to raise a rebellion of the Jaffa against the Goa’uld, when he is betrayed and captured.
Apophis, after the death of Sokar in “The Devil You Know”, (Sokar, despite his supposed power and the fear he apparently installed in his enemies, was not a threat for very long) has control of Sokar’s forces, and is becoming the most feared and powerful Goa’uld System Lord. He is on the verge of taking control of the entire Goa’uld System Lord system with an alliance with Heru’ur. A big step up from where he was at as a captive of Sokar.
The Tok’ra plan to sabotage the alliance before it happens, and by doing so cause Heru’ur and Apophis to spend their forces fighting each other, and ask the rest of SG-1 to help.