4 vault." Tarling nodded.
"I need not ask you whether the books which Mr.Milburgh brought this morning had been placed in that safe, Sir Felix," he said, and the knight looked surprised.
"Of course not.

They were placed there whilst you were in the office," he said.

"Why do you ask ?" "Because in my judgment those books were not books at all in the usually understood sense.

Unless I am at fault, the parcel contained three big ledgers glued together, the contents being hollowed out and that hollow filled with thermite, a clockwork detonator, or the necessary electric apparatus to start a spark at a given moment." The accountant stared at him.
"You're joking," he said, but Tarling shook his head.
"I was never more serious in my life." "But who would commit such an infernal act as that?
Why, one of my clerks was nearly burnt to death!" "The man who would commit such an infernal act as that," repeated Tarling slowly, "is the man who has every reason for wishing to avoid an examination of Lyne's accounts." "You don't mean---- ?" "I'll mention no names for the moment, and if inadvertently I have conveyed the identity of the gentleman of whom I have been speaking, I hope you will be good enough to regard it as confidential," said Tarling, and went back to his crestfallen subordinate.
"No wonder Milburgh was satisfied with the forthcoming examination," he said bitterly.

"The devil had planted that parcel, and had timed it probably to the minute.