The Doctor, Susan, Ian and Barbara land on Hydra, where Admiral Jonas Kaan leads a flotilla of ships trying to elude the vicious race that has invaded their world. But his ships are being picked off one by one, dragged underwater by an unseen foe...
- ISBN10 1781783365
- ISBN13 9781781783368
- Publish Date 30 September 2014
- Publish Status Out of Print
- Out of Print 14 May 2021
- Publish Country GB
- Imprint Big Finish Productions Ltd
- Format Audiobook
- Pages 120
- Language English