The window was pried up swiftly but silently and the detective slipped in, his example being imitated at once by the others.
They found themselves in a large kitchen, which was brightly lighted, and which gave evidence that Hoff had been there very recently, probably at the time of the explosion, for there was a dishpan in the sink and dishes in the draining rack alongside.
In their previous study of the windows they had learned that there was a rear stairway, for they had often seen Hoff passing a small window as he went up and down.
They had reason to believe that the operating room was on the second floor, somewhere in the center of the house, and they meant to reach it, if possible, by way of the rear stairs.
In fact, that was their only hope of doing so unobserved, since they could not count on the bomb having emptied the house completely.
The door from the kitchen into the lower hall had been left open, and Nick and his friends dodged through it. Fortunately, the hall contained a turn, which shut them off from observation on the part of those on the front stairs and at the door.
They heard hurried footsteps descending the other stairs, however, and concluded that several persons were clustered about the front door.
The rear stairway was easily located, and they started upward with as much care as their desire for haste permitted. It was no part of their plan to leave the house again without being seen. They knew that was practically out of the question. However, they wished to see as much as they could before they were discovered, and were, naturally, anxious to find something that would justify their intrusion before Doctor Grantley became aware of their presence.
But luck was against them.
When they reached the head of the servants’ stairs, they saw the open door of an unusually brightly lighted room about fifteen feet ahead of them.