A canine species with shiny black skin were called "foxes" by the humans on Iwa, due to their appearance. They were highly intelligent, had psychic abilities and could undergo complete molecular disassembly, before being reassembled elsewhere. The First Doctor theorised that this ability was genetically engineered, rather than evolved.

The "foxes" came to Iwa seeking the services and facilities of the humans stationed there, and at first contact killed three of their soldiers. A bloody war ensued, which lasted months. They eventually gained access to the facility known as the Refuge, establishing control over the base and forcing the humans to work for them to achieve their goal. With the knowledge the "foxes" would leave once their goal was achieved, the First Doctor and Susan quietly slipped away from the planet. (PROSE: Frayed)