Its hiding-place must be somewhere handy, Charlie reflected, for at least half a dozen times a day the old man passed that iron barrier which shut off the upper part of the mansion. He wondered where he could find that key, but remained wondering.
That evening he took the impression of the latchkey to Dover Street, and with Max’s help tried to fashion a key to that pattern, but though they tried for hours it was in vain. So they gave it up. Next day Max took train to Birmingham, and handed the impression to a locksmith he chanced to know. The latter, having looked at it, shook his head, and said:
“This impression is no use, sir. It’s what they call a paracentric lock, and you must have impressions of both sides, as well as the exact width back and front before I can make you a duplicate.”
The man showed how the impressions should be taken. Max, of course, concocting a story as to why it was wanted, and then back to London he travelled that same night to consult with his friend.
The outcome of this was that two days later complete impressions were taken of the small latchkey, and within three days came the duplicate by post.
Max bought two electric torches, two pairs of felt slippers, a piece of thin but very strong rope, screwdriver, chisel, and other implements, until he had a full burglar’s equipment. The preparations were exciting during the next few days, yet when they came down to bed-rock fact there was that locked door which stood between them and the truth.
Charlie’s object in obtaining a duplicate latchkey was to enter noiselessly one night shortly before eleven, and secrete, themselves somewhere until Levi bolted the door and retired. They must take their chance of making any discovery they could. Both were well aware of Levi’s vigilance, and his quickness of hearing. Therefore they would be compelled to work without noise, and also to guard against any hidden electric burglar alarms which might be secreted in the sashes of windows or in lintels of doors.
Investigation by Charlie had not revealed the existence of any of these terrors to thieves; yet so many were the precautions against intruders that the least suspected contrivance for their detection was to be expected.
Nearly a fortnight passed before all arrangements were complete for the nocturnal tour of investigation. Daily Rolfe, though attentive to his duties as the old man’s secretary, was always on the alert to discover the existence of that key to the iron door. By all manner of devices he endeavoured to compel Statham to unwittingly reveal its whereabouts. He made pretence of mistaking various keys to deed boxes and nests of drawers, in order that the old man should produce other keys. But he was too wary, and never once did he fall into the trap.
Yet often he left the study, passed up the stain, and through the door swiftly, until the younger man began to suspect that it might be opened by means of some secret spring.