Mede 1

A Mede and its associate came to Earth in the year 2050. They were captured by Inspector Drake and the Department and imprisoned. Drake attempted to use their technology to spy on the people of London. The attempted replication of their technology caused chenium to leak into the River Thames, polluting it. The Medes tried to communicate with K9 and the gang, their avatar forms directing K9 to the source of the pollutions. June used her authority to shut down the project. June and the gang then went to the Dauntless Prison and released the Medes, returned their technology, and apologised for their capture. They removed the pollution from the river Thames and returned home. (TV: Alien Avatar)