The Mystery of the Singing Serpent — M.V. Carey

A strange, shrill song echoes through the old Jamison mansion. The housekeeper flees from the estate, screaming in terror. Young Allie Jamison blames a houseguest, Mr. Ariel, for the spine-chilling noises. He's an odd little man who never sees daylight. And he holds some mysterious power over Allie's eccentric aunt.

Allie asks The Three Investigators to chase Ariel away. But Ariel is protected by powerful forces -- evil spirits and a singing snake!