By the Pricking of My Thumbs

'By the pricking of my thumbs
Something wicked this way comes.'
MACBETH
When Tommy and Tuppence visit an elderly aunt in her gothic nursing home, they think nothing of her mistrust of the doctors; after all Ada is a very difficult old lady.
But when Mrs Lockett mentions a poisoned mushroom stew and Mrs Lancaster talks about 'something behind the fireplace', Tommy and Tuppence find themselves caught up in an unexpected adventure involving a strange inheritance, a mysterious house, black magic, a missing tombstone - and almost death for the redoutable Tuppence...
'The most macabre and eerie Christie I have read for a long time.' Sunday Express
'Mystery at the usual high Christie level.' Evening Standard