But the night watchman when roused from his sound forenoon's sleep was certain that no one had entered the building on the previous evening save those who had business there.
"Everybody's got to use a pass now, you know," he stated. "I was on the job all night myself an' divvle a bit of anything out of the ordinary did I see. There was Mr. McNight and Mr. Lester and Mr. Greene on the job in the telegraph room, and the usual crowd of correspondents over in the press room, and a score of others who works there regular, an' Mrs. Prentice, an'—"
"Mrs. who?" interrupted Taylor.
"Mrs. Prentice, wife of th' Third Assistant Secretary. She comes down often when her husband is working late, but last night he must have gone home just before she got there, for she came back a few minutes later and said that the office was dark."
Whatever Taylor's thoughts were at the moment he kept them to himself—for Prentice was the man from whose safe the cipher key had been abstracted!
So he contented himself with inquiring whether the watchman was certain that the woman who entered the building was Mrs. Prentice.
"Shure an' I'm certain," was the reply. "I've seen her and that green evening cape of hers trimmed with fur too often not to know her."
"Do you know how long it was between the time that she entered the building and the time she left?" persisted Taylor.
"That I do not, sir. Time is something that you don't worry about much when it's a matter of guarding the door to a building—particularly at night. But I'd guess somewhere about five or ten minutes?"
"Rather long for her to make her way to the office of her husband, find he wasn't there, and come right back, wasn't it?"