Sixth DoctorPeri Brown
Gary RussellJason Haigh-Ellery
The Sixth Doctor and Peri attend a conference of lexicographers at a college where an unfortunate murder has occurred. The victim was a perfectionist linguist compiling the galaxy's biggest dictionary, and also a personal friend of The Doctor, but the only suspect is her holographic assistant, named Book, who is also a repository for every word in the English language.
The Omniverbum is the mythical longest word in existence. According to records, no one who has found the Omniverbum, or its sentient affix "Ish", has lived to tell of it. Except one. Book found the Ish on an obscure world and accidentally brought back to the college as per his programming. But now it's escaped, and is out to cause havoc on the speech centers of the human brain unless The Doctor can stop it.
Peri is in a different kind of danger. Swiftly falling in with a so-called "word anarchist" named Warren, she might come face to face with the slowly degenerating Book, who is distraught and unhinged over his master's death by possibly his own hands. Distraught and unhinged enough to kill her....