Detective Mallory was an able man, the ablest, perhaps, in the bureau of criminal investigation, but a yellow primrose by the river's brim was to him a yellow primrose, nothing more. He lacked imagination, a common fault of that type of sleuth who combines, more or less happily, a number eleven shoe and a number six hat. The only vital thing he had to go on was the fact that Miss Danbury was dead--murdered, in some mysterious, uncanny way. Vampires were something like that, weren't they? He shuddered a little.