Caius' betrayal is a troubling wrinkle. It points towards another, more dangerous, organization. Our intelligence indicates that this may be the Shadow Council. The council's base of operations is Shadow Hold, in Felwood. If our information is correct, Caius' ritual will likely be performed there. You must infiltrate Shadow Hold, find Caius, and stop him. It is imperative you remain undetected. If Caius catches wind of your presence, he is likely to flee, or have you killed.