__ of Fate, Last Book Agatha Christie Wrote
Puzzle 3 of Agatha Christie Medium Pack
Question is: __ of Fate, Last Book Agatha Christie Wrote
and the answer is: POSTERN
Word Meaning:
POSTERN — (architecture) A back gate, back door, side entrance, or other gateway distinct from the main entrance, especially in a city wall or fortification.
Definitions from Wiktionary.