The Great God Gold by William Le Queux

Christmas had passed, the New Year had been welcomed, its advent quickly forgotten, and London now lay dark and fog-bound in the yellow gloomy days of mid-January.

As far as Professor Griffin was concerned, little had occurred. His surprise when Gwen had told him of Erich Haupt being interested in the investigation of the secret was unbounded, and he had taken a cab at once to the Waldorf Hotel. He was anxious to meet the great German scholar, but was disappointed to learn that he had suddenly left the hotel on the previous night for the Continent.