Sir Arthur Conan Doyle, master of mystery and suspense, has penned a short story worthy of his title.

Marshall King is in dire straits. With his finances waning, he must seek help or be ruined. His wealthy uncle is a miserly old fellow, unwilling to help out a relative. And so Marshall goes to visit his adventurous and wealthy cousin, Everard, who has just settled back in England after time spent in Brazil. Marshall is cordially welcomed by his cousin, though Everard's wife regards him with cold rudeness. After an encounter with Everard's black, carnivorous—and enormous—Brazilian cat, various motives are brought to light.