Once—twice—thrice—and up swung the ladder:—that single blow was sufficient—and the trap-door burst from its setting. Quick as thought, Rainford seized his pistols, and thrusting up the trap, ascended the last few steps of the spiral staircase. Throwing back the carpet which had been replaced over the trap-door, he found, to his infinite surprise, that there was no resistance to his egress from that subterranean where, at one time, it seemed probable that he was destined to find a tomb; and, gazing rapidly around the room, he neither perceived Old Death nor the Doctor—nor indeed a single living soul. Recovering all his wonted calmness, he proceeded to examine the trap-door, for the purpose of ascertaining how it had been secured against him: and, on a close inspection, he observed a spring-bolt let into the side of the trap-door in such a way that, when the trap was closed, it neither appeared above nor below it. This bolt was either held back within the wood, or made to fly into a hole made to receive it in the beam against which the trap-door closed, by means of two screws that could easily be pressed inwards. But the force of Rainford's battering-ram had unsettled this artfully-contrived piece of mechanism. It was clear that some one had secured the trap-door; because even if the spring-bolt had flown into its socket by accident, still the carpet could not have spread out of its own accord. Moreover, when Rainford had retreated to the subterranean, he had heard footsteps and voices in Old Death's room. It therefore struck him that those who had so secured the trap-door, had departed to protect the avenue of escape in Turnmill Street, in the confidence that the said trap-door was too strong to be forced. Nevertheless, it was necessary to guard against the possibility of an ambuscade; and Tom held his pistols in a manner calculated to render them instantaneously available. He determined to proceed by way of the laboratory; but, on trying the door, he found it locked. Without an instant's hesitation he forced it open with one vigorously applied blow of his foot: but here again he encountered no resistance. Passing through the laboratory, he tried the door by which he had seen Dr. Lascelles appear and disappear again so abruptly; and this time he was spared the necessity of violent exertion,—for the door was not locked. He now entered a passage leading to a flight of stairs; down which he hastened, and reached a kind of hall, from whence the street-door opened. But he did not immediately issue forth. He experienced an invincible curiosity to ascertain if Old Death had in reality been released from the state of bondage in which he had left him; and, forgetting the terrible dangers whence he had escaped with so much difficulty, he re-ascended the staircase.