Professor Bernice Summerfield and the Poison Seas

In 2003, Professor Bernice Summerfield and the Poison Seas was released by Big Finish Productions.

Cover blurb
Bernice has visited the planet Chosan before, so she seems the ideal candidate to intervene when a Sea Devil colony there comes under threat from a terrorist cell. Under cover of visiting an old friend, Bernice sets out to learn who is working in league with the terrorists to ensure the eradication of the colony.

But as she delves deeper under the oceans of Chosan, she discovers that something else -- something much more ancient and powerful -- ­wants rid of the Sea Devils. Soon, every living thing on the planet is in peril. And all because there’s no place like home...