[By the Pricking of My Thumbs is a] mystery centered on senior citizens which will nevertheless appeal to younger girls. Tommy and Tuppence Beresford visit an aging aunt in a rest home, and a few stray remarks by a supposedly senile companion lead to revelations concerning crimes of infanticide which had long been thought solved. The clues occasionally come too fast and heavy, and at times there are too many characters, but all is neatly tidied up in the end. Particularly good is the way the confused, befuddled, genteel and elderly Beresfords, the woman working from womanly intuition and the man from reason and logic, plow through the morass of hints and suspicions to finally half-deduce, half-stumble on the answer to the mystery. Competent Christie, in its own way bridging the generation gap. (p. 1346)

Marcia Keller, in Library Journal (reprinted from Library Journal, March 15, 1969; published by R. R...