Edge of __, Labyrinthine Thriller Starred Bob Peck
Puzzle 16 of TV Classics Easy Pack
Question is: Edge of __, Labyrinthine Thriller Starred Bob Peck
and the answer is: DARKNESS
Word Meaning:
DARKNESS — (uncountable) The state of being dark; lack of light; the absolute or comparative absence of light.
Definitions from Wiktionary.