Deep Blue (novel)

 was the twentieth BBC Past Doctor Adventures novel. It featured the Fifth Doctor, Tegan Jovanka and Vislor Turlough. It also featured UNIT, Brigadier Alistair Gordon Lethbridge-Stewart, Captain Mike Yates and Sergeant John Benton. Also, it sees a character development for Tegan, with her falling in love in this novel.

Publisher's summary
''When a lighthouse keeper reports seeing a ball of light plunging into the sea off Tayborough Sands, UNIT sends Mike Yates to investigate. The last thing he expects to find there is an old friend — with a new face...'' The Doctor and his companions arrive on a pleasure beach in the 1970s, hoping for time off after their latest adventures. But they do not get to relax for long. Violent incidents are at an all time high in the area and people are going missing - or else changing into something more than human...

The Doctor soon realises a sinister presence lurks in the cold seas off Tayborough Sands - a presence with sinister designs on humanity.

Plot
to be added

Characters

 * The Doctor
 * Tegan Jovanka
 * Turlough
 * Brigader Lethbridge-Stewart
 * Mike Yates
 * Sergeant Benton
 * Derek Etkins
 * PC Andy Weathers
 * Tony Maybury
 * Imogen Maybury
 * Charlotte Maybury
 * Chris Maybury

Spacecraft

 * The ship that invades is a modified Morok battlecruiser.

Technology

 * The Doctor uses the IRIS machine

Continuity

 * From UNIT's point of view, this story takes place after TV: The Green Death.
 * Mike Yates is still recovering from the events of The Green Death.
 * The Doctor mentions the Zygons. (TV: Terror of the Zygons)