A Bid for Fortune or Dr Nikola's Vendetta

This is the first in Boothby's series of Dr. Nikola novels. It opens with the manager of a fine London restaurant preparing for a dinner reserved in an odd letter originating from Brazil 3 months prior, for 4 persons in a private room, where 3 guests will arrive showing cards with a red dot. One will be from China, one from South Africa, one from England, plus the host, Dr Nikola, who is of unknown nationality but is later revealed to travel the world widely. The letter specifies certain preparations, such as no electric lighting but rather candles with red shades, a small jug of fresh milk, and a porcelain saucer.