Subterranea (audio story)

 was the sixth story in the sixth series of the Fourth Doctor Adventures, produced by Big Finish Productions. It was written by Jonathan Morris and featured Tom Baker as the Fourth Doctor and Lalla Ward as Romana II.

Publisher's summary
The TARDIS is going underground. When the Doctor and Romana find themselves buried beneath the surface of an alien world, they're soon swallowed up by a giant burrowing machine. This is where the inhabitants of this planet live - in huge, constantly moving, Drill-towns, chewing up the fuel and resources of the planet in order to survive.

But something else lurks in the earth. Something that feeds on the Drill-towns. Something that is relentless and will not stop.

The Silex are hunting.

Part one
to be added

Part two
to be added

Cast

 * The Doctor - Tom Baker
 * Romana - Lalla Ward
 * Mr Maxwell Wilberforce Bell - Matthew Cottle
 * Mrs Lucretia Bell - Abigail McKern
 * Mr Jelicho Wigg / Mr Wilfer Wagstaff - Robbie Stevens
 * Miss Arabella Wagstaff / Mrs Betsy Wagstaff - Jane Slavin
 * Silex / Mr Stroker - John Banks

Continuity

 * Romana says "Oh, look. Rocks." (TV: Destiny of the Daleks)
 * Romana is still using her sonic screwdriver. (TV: The Horns of Nimon)