Koko is Qwill's male Siamese cat with aristocratic sensibilities and an epicurean appetite. Although Qwill is credited with assisting the police in Down Below on several investigations, it is actually Koko who sniffs out the clues. Shortly before Qwill finds the daisy mural in the servants' quarters, Koko plays the tune "Daisy, Daisy" on the piano. Koko is nowhere to be found while Qwill gives Melinda a tour of the mansion, but Qwill eventually finds the cat in a far corner of the attic, scratching a carton labeled "Daisy Mull" which contains winter clothes, a maid uniform and an ivory elephant from Amanda's studio. When Qwill, Melinda and Koko return downstairs, Qwill confides that Koko has "an uncanny talent for finding objects of significance" (page 80). Koko also kicks Melinda out that night. Another day, Koko runs to the attic, and Qwill chases him until Koko allows himself to be caught while sitting on a suitcase tagged "Daisy Mull" which contains summer clothes, jewelry, cosmetics and baby clothes.