Daenerys and Ser Jorah talk to Kraznys mo Nakloz here about purchasing some Unsullied as an army in episode #301 "Valar Dohaeris". Daenerys, Ser Jorah, and Barristan Selmy walk past the slaves strung up to die here and Daenerys attempts to give one of them her water in episode #303 "Walk of Punishment". The three later meet with the Good Masters here and Dany agrees to sell one of her dragons for all of the Unsullied in episode #303 "Walk of Punishment".