Full Fathom Five (audio story)

 was the third Doctor Who Unbound audio story produced by Big Finish Productions. It featured David Collings as the Doctor. Unlike the previous two stories this story's Unbound scenario is not immediately apparent, but as the story unfolds it is revealed to be a scenario of "What if the Doctor believed the ends justified the means?", taking the story and the character of the Doctor into darker and harsher territory than has previously been explored.

Publisher's summary
What if...?

"If I told you the truth, I'd have to kill you..."

The Deep-sea Energy Exploration Project was apparently destroyed by dirty bombs in 2039 AD, turning the surrounding sea bed into a radioactive tomb. Rumours suggest the DEEP was conducting illegal, unethical experiments...

In 2066, the Doctor discovers the research centre remains intact. The terrible truth about what happened twenty-seven years ago will soon be revealed. The Doctor is determined to be the first to uncover and confront the secrets of the DEEP.

But unearthing the past can have terrible consequences for your future...

Plot
to be added

Cast

 * The Doctor - David Collings
 * General Flint - Ed Bishop
 * Ruth - Siri O'Neal
 * Hoskins - Jeremy James
 * Professor Vollmer - Matthew Benson
 * Lee - Jack Galagher
 * The New Doctor - Ian Brooker (credited on Big Finish website only)

Continuity
to be added