Zinn

 was the dowager of the Jade Chordata. She was worried about a broken promise and argue with the Grand Widow. She wanted to execute the Third Doctor and Jo Grant. She later murdered the Grand Widow. She worked with Chusa to get her line on the throne so that Zinn could control Draconia. Emerald Lindstrom realised that her ambitions also went to Earth. After learning the truth, Chusa killed Zinn and himself. (AUDIO: Conspiracy in Space)