Therefore, its known narrative elements are not a part of the Doctor Who universe. It may have been the basis for a similar story in another medium, however — and that story may indeed be a part of the DWU.
Hostage would have been a three part story "about an elite group of soldiers sent after shape-changing criminals Butler and Swarfe, who had stolen a new weapon and taken it to an overgrown jungle planet. The end of the first episode had Swarfe change in full view into a monster, before it went on the hunt in the second episode. The Doctor and Ace were involved and it turned out that the planet was the last battleground between the Time Lords and the Scaroth. The end piece was set in a castle — the whole thing had a fairy tale feel — where the criminals intended to ignite the bomb. It was Doctor Who meets Predator and Aliens."