"Guilt"

The ​​​​​​​work – “Guilt” was based on the ideology; “Guilt is never to be doubted”, which over decades, proved to be key in Christie’s plots. The metaphor in play was the one of washing one’s guilt-ridden hands and yet not being able to get rid of it. The B&W-ness refers to the stark duality of concepts of good and evil, which foster guilt.