Angel Esquire

This is a crime mystery novel by Edgar Wallace. The wealthy owner of a gambling establishment dies, leaving his money in a mysterious safe. This safe is built on a pillar and it also occupies an entire building. The safe is left for whichever of his potential heirs, who can solve the complex puzzle. The title of this novel comes from the Scotland Yard detective Christopher Angel, who becomes involved with the case. Angel Esquire must ensure that youth and innocence triumph. Who will solve the puzzle? Is it the innocent young girl whose father was swindled by the wealthy owner of the gambling establishment?