Fungus (short story)

Fungus was a short story from the 1984 Doctor Who annual. It unusually featured a companion-less Fifth Doctor meeting up with a previously-unseed "old friend" called Professor Lloyd and having an adventure that was almost exclusively laboratory-bound.

Summary
Somewhere in the United Kingdom, a young woman called Edith Stevens is attacked by her cat, Boris. Elsewhere in the country, Professor Lloyd informs the Fifth Doctor of the epidemic of cat attacks like Boris' that are sweeping the nation.

The Doctor immediately begins investigating his old friend's problem. He uses his heightened olfactory senses to determine that something about the milk in his tea is "off". Lloyd's human senses aren't keen enough to detect anything, so the Doctor is forced to prove it through careful examination of the milk. He discovers a fungus that he enigmatically says that he's seen before. When asked why the milk isn't affecting other animals, like humans, the Doctor surmises that cats are simply particularly susceptible.

The time traveller then begins to question Lloyd about the current origin of Britain's milk. The Time Lord is surprised to discover that the tanks in which the milk is being stored comes from Houston, Texas. Somehow, the fungus has spread from outer space to the Houston-made milk vats to the cats of Britain.

The Doctor uses his previous knowledge of the fungus to develop a quick solution: a high-pitched sound, as delivered from a dog whistle, will successfully knock out the virus. He leaves it in Lloyd's hands to get the government of Britain to co-ordinate short bursts of sound from radio stations around the country.

Characters

 * Fifth Doctor
 * Professor Lloyd
 * Edith Stevens
 * Boris

Continuity

 * The Doctor makes significant use of a dog whistle in the story. Though unusual for the Fifth Doctor, it was a tool that he sometimes used in his previous incarnation to call K9.
 * The professor is constantly irritated by the enigmatic way in which the Doctor pieces together the puzzle. The Doctor's habit of dropping clues without fully explaining them fully is fairly consistent amongst all incarnations, and echoes a dynamic present in several Doctor/companion relationships, like First Doctor/Ian, Third Doctor/Brigadier, and even Eleventh Doctor/Jenny/Vastra.