Recommended reading - One Across, Two Down (1971):

One Across, Two Down

By Ruth Rendell.

Filmed as Diary of the Dead (1976), directed by Arvin Brown.

Published by Vintage Crime / Black Lizard.

First published 1971.

ASIN: 0375704949

ISBN-10: 9780375704949

ISBN-13: 978-0375704949

Description:

Two things interest Stanley Manning: crossword puzzles, and the substantial sum his wife Vera stands to inherit when his mother-in-law dies. Otherwise, life at 61 Lanchester Road is a living hell. For Mrs. Kinaway lives with them now – and she will stop at nothing to tear their marriage apart. One afternoon, Stanley sets aside his crossword puzzles and changes all their lives forever...

In One Across, Two Down, master crime writer Ruth Rendell describes a man whose strained sanity and stained reputation transform him from a witless loser into a killer afraid of his own shadow.  Mischievously plotted, smart, maddeningly entertaining, One Across, Two Down is a dark delight – classic Rendell.

"The best mystery writer in the English-speaking world." – Time.