Miss Pongleton was unpleasant. Miss Pongleton was vindictive. Was that why Miss Pongleton was dead - strangled with her own dog's leash on a stairwell on the London Underground's Northern Line?

A sudden death, a mysterious cipher that could not be broken, and strange goat-like footprints all combine to terrorize a young woman in a remote house.

Cornelia Potts was the unpleasant old woman in the shoe, and some of her six children clearly were mad. Mad enough to murder? That's what Ellery Queen needed to find out.

What secret caused a doctor to disappear from his home without any warning - or several other people apparently to vanish as well? Scotland Yard's Inspector French will find himself challenged when murder enters the picture.