Tom Baker - (The Doctor)

Louise Jameson - (Leela)

John Leeson - (Voice of K9)

Michael Sheard - (Lowe)

Brian Grellis - (Safran)

Edmund Pegge - (Meeker)

Jay Neill - (Silvey)

Anthony Rowlands - (Crewman)

John Leeson - (Nucleus Voice)

Frederick Jaeger - (Professor Marius)

Roy Herrick - (Parsons)

Elizabeth Norman - (Marius' Nurse)

Nell Curran - (Reception Nurse)

Jim McManus - (Opthalmologist)

Roderick Smith - (Cruikshank)

Kenneth Waller - (Hedges)

Pat Gorman - (Medic)

John Scott Martin - (Nucleus)

A three-man shuttle crew are completing the final stages of their journey to Titan base, when a course deviation puts the shuttle in the path of a mysterious cloud in space.

The crew members arrive on Titan, but they have been somehow changed, infected by an intelligent virus that threatens everyone in the galaxy. The TARDIS picks up a Mayday message from Titan base, but before the Doctor and Leela can fully respond, the police box also passes through the mysterious cloud. With the infection spreading from person to person, the Doctor and Leela seek assistance on a medical station in the asteroid belt.

As the situation worsens, their only hope lies in the unlikely combination of the eccentric scientist Professor Marius, and his dog-shaped computer K9...

Working Title:

The Invader Within, The Invisible Invader

Things to look for:

• Coming Soon. 

The Doctor Who Archive:

The complete unedited reel exists.

Bloopers:

Coming Soon

Title Information:

• The Invisible Enemy
• Episodic format
• UK PAL - Released September 2002
• BBC Video cat.#7267

Not yet released on DVD.

Not yet released on Audio.

Title Information:

• Doctor Who and The Invisible Enemy
• Written by Terrance Dicks
• Manufactured by Target
• Published 1979
• No.36 in the Target, Doctor Who Library.