The Secret House w/ Direct link technology (A Mystery Classic)

He took from his waistcoat pocket a newspaper cutting and compared the two then stepped briskly, almost jauntily, into the hall, as though all his doubts and uncertainties had vanished, and waited for the elevator. His coat was buttoned tightly, his collar was frayed, his shirt had seen the greater part of a week's service, the Derby hat on his head had undergone extensive renovations, and a close observer would have noticed that his gloves were odd ones.
He walked into the lift and said, "Fifth floor," with a slight foreign accent.
He was whirled up, the lift doors clanged open and the grimy finger of the elevator boy indicated the office. Again the man hesitated, examining the door carefully. The upper half was of toughened glass and bore the simple inscription: