Five years before, Rolfe’s father, a man of considerable means who had been interested in his financial undertakings, burnt his fingers badly over a concession given by the Persian Government and became bankrupt. A year later he died, a ruined man, leaving a son Charles and a daughter Marion. The latter had been compelled, he understood, to earn her living in a London shop, and the former, who had only recently come down from Oxford, he had engaged as his confidential secretary.

He had indeed done this because he had felt that Charlie’s father had made the ruinous speculation upon his advice, and it therefore behoved him to do some little for the dead man’s children. Few men in the City of London in these modern days are possessors of consciences, and those who have are usually too busy with their own affairs to think of the children of ruined friends.

Old Sam Statham was a hard man, it must be admitted. He would drive a bargain to the last fraction of percentage, and in repayment of loans he was relentless sometimes. Yet the acts of private charity that he did were many, and he never sought to advertise them.

In Charles Rolfe he had not been disappointed. Never once had he disobeyed the orders he had given, and, what was more, never once had he sought to penetrate beyond the door at the head of the staircase which shut off the ground floor from the one above.

The first day that Rolfe came to attend to his correspondence he had told him that he must never ascend those stairs, and that if he did he would be discharged at a moment’s notice.

This prohibition struck the young man as curious and lent additional colour to the whispers of mystery concerning the fine fashionable house. A thousand weird suggestions arose within his mind of what was concealed upstairs, yet he was powerless to investigate, and, after a few weeks, grew to regard his master’s words as those of an eccentric man whose enormous wealth had rendered a trifle extraordinary at times.

Old Levi was janitor of that green baize door. Situated round the corner, no one standing in the hall could see it. Therefore its existence was unsuspected. But it was an iron door covered with green baize, and always kept locked. Levi kept the key, and to all Rolfe’s inquisitiveness he was dumb.

“The master allows nobody upstairs,” was always his reply. “I sleep downstairs because I am not permitted to ascend.”

What other servants might be there he knew not. Levi was the only other person he ever saw. The curtains at the upper windows always looked fresh and smart, and often as he went up Park Lane at night and glanced up at them, he saw lights in them, showing that they must be inhabited.

At first all this puzzled him sorely. He had told Marion about it, and also Maud Petrovitch, both girls being intensely interested in the mystery of the house and the character of the unseen occupants of its upper floors.