Grand Marshal Jastrok was the leader of a Silurian clan at Scafell.

He started to attack UNIT when they visited their base. The Third Doctor knew of him and told UNIT to be wary of him. He managed to get to the White Hart and started to attack John Benton, Mike Yates, Kate Stewart and Petronella Osgood. (AUDIO: Call to Arms)

He later sent Anthony Burmaster to wake up a Sea Devil colony. (AUDIO: Tidal Wave)

Later he sent Tryska after Kate and Osgood to stop them getting a control device and a fear inducing machine. (AUDIO: Retrieval)

He started to seize control of the UK, and he went to London to get the humans' surrender. Josh Carter and Mike Yates went to negotiate with him but all he wanted was their surrender. When it started snowing, he ordered Kalana to set of the Nuclear Weapons. He was placed in deep hibernation under the Black Archive to be dealt with by his own people. (AUDIO: United)

Community content is available under CC-BY-SA unless otherwise noted.