Mede 2

A Mede and its associate came to Earth in the year 2050. They were captured by Inspector Drake and the Department and imprisoned. Drake tried to use their technology to spy on 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, using their avatar forms to direct K9 to the source of the pollution. June shut down the project. The gangand she went to the Dauntless Prison and released the Medes, returning their technology and apologising for their capture. They cleared the pollution from the Thames and returned home. (TV: Alien Avatar)