 Oliver, a university lecturer with an obsession for anagrams and crosswords, has been a question-setter for "Mastermind". When made redundant by the new Vice-Chancellor of the New University (his former Polytechnic) in a general restructuring of the university, Oliver decides to use his new-found freedom to search for his favourite crossword compiler, known only by the pseudonym of "Aristotle". When he locates "Aristotle s" Welsh home, he is horrified to find that it has been burnt down. He goes to the local police station to report "Aristotle" as a missing person and, while there, meets Diane Priest, a policewoman who, Oliver claims, is his  predestined  companion. Oliver invites Diane to join him in his travels and later, when she is suspended from duty by her superiors, she decides to do so - joining Oliver in his search for "Aristotle". From that moment on, they share many life-threatening situations (as well as mutual love) before their quest for the elusive "Aristotle" comes to a final and gripping conclusion.