In the Dead of Night by John T. McIntyre

Steele Kenyon, a young American who had lived in all kinds of places, fought in revolutions in South America, and done all kinds of things except make a financial success out of his life, returns to New York with ten dollars in his pocket. With his last remaining money, he proceeds to dine well...possibly for the last time.

Later that evening, while wandering the Great White Way and reflecting on his life, a young woman pulls up in an taxi and bids him enter...and launches him into enough mystery and adventure to last a lifetime!