The moving finger

Lymstock is a town with more than its share of shameful secrets - a town where even a sudden outbreak of anonymous hate-mail causes only a minor stir.

But all that changes when one of the recipients, Mrs Symmington, commits suicide. Her final note said I can't go on. Only Miss Marple questions the coroner's verdict of suicide. Was this the work of a poison-pen? Or of a poisoner?
 Reviews

"Beyond all doubt the puzzle in The Moving Finger is fit for experts."
The Times