And another Agatha Christie book is also on sale for $1.99 in the US:
Dumb Witness, which is the sixteenth in Christie's Hercule Poirot series.
Kindle US:
https://www.amazon.com/Dumb-Witness-...dp/B000FC2RRM/
Kindle US/Smile:
https://smile.amazon.com/Dumb-Witnes...dp/B000FC2RRM/
Kobo US:
https://www.kobo.com/us/en/ebook/dumb-witness