Then they heard that padding footstep, and Margaret instinctively grasped Peter's arm. It came nearer, and then stopped. The shutter slid back, and once more they saw the cowled face at the grille. For perhaps fifteen tense seconds the eyes they could see through the slits observed them. Then, just as Peter had thumbed down the safety catch of the pistol behind him, the shutter closed again, and the footsteps passed on.
Margaret was shaking. "I don't think I can bear it for much longer," she whispered.
They heard the grate of a key, and knew that the Monk had unlocked the door into the printing-room. There was a long, long pause. Once they thought they heard the soft footfall again, but they could not be certain.
Another hour crept by. Margaret felt cold, and rather sick. "It's - it's like waiting at the dentist's when you're going to have a tooth out," she whispered, trying to smile.
Even as she said it they heard footsteps approaching, and the murmur of voices.
"The rest of the gang," Peter said. "Feeling all right, Sis?"
She grimaced, but nodded.
The voices drew closer: they heard the same man who had brought the water on the night previous, say: "Well, this is my last night, and I don't care who hears me say it. Things are getting a sight too hot for me."
Someone, probably Wilkes, Peter guessed, said something in a low voice. "Let 'em hear!" the other replied. "They won't hear much after to-night." Then the voices ceased, and in a few minutes the roar of the engine started.
It seemed to the two who waited in their cell that hours passed. Margaret looked at Peter with a scared question in her eyes. He put his lips to her ear. "Don't forget they had to wait for the signal. "Tisn't as long as we think, Sis. Don't fuss!"
They relapsed into listening silence again. "Difficult to hear above the row of the engine," Peter said.
But he too was beginning to wonder whether any hitch had occurred. Then the shutter slid back, and they saw Michael's face for a moment. Peter went to the door, and Michael whispered: "I'm going to draw back the bolts, but whatever you do, don't come out till you're given the word." He disappeared as he spoke; they heard the bolts drawn cautiously back, and then Peter beckoned Margaret to come and stand out of range of the grille.
Outside in the passage, the four other men had halted behind Michael. A stream of light came from the room beyond Peter and Margaret's cell, and they knew that the men were working with the door open, probably for the sake of air.
Michael gave the signal, and they crept forward.
Michael and Tomlinson reached the door together. "Hands up!" Michael said. "The first man who moves I shoot!"
Even as the words left his mouth there was a report, and the light went out; someone had fired at the electric bulb, and the place was plunged into sudden darkness.
But in that brief moment Michael had had time to see the whole room in one lightning glance. Wilkes was there, working the central machine; the two other men were there, but there was no sign of the Monk.
In a moment there was turmoil. A gun cracked, and the inspector's revolver answered it. Someone's torch lit up a corner of the room for a brief instant, then there was a scuffle in the doorway, another shot, and a wild struggle in the passage. Above the noise of the engine and the fight, Michael shouted: "He's not here! Collar those men!" He felt a shot whistle past his head, ducked, and ran back down the passage, a gun in one hand, his torch in the other.
Behind him the noise grew fainter and fainter; he could safely leave Inspector Tomlinson to deal with the three others but something far more important remained to be done. The Monk had not been in the printingroom. Michael had a sickening fear that there was some other entrance he had failed to discover, but the first thing to do was to race for the crypt, in case the Monk had gone that way. As he ran he cursed himself for not having taken the precaution to go up the stairs past the library before he led the police down. The Monk must have been on the stairs when they came through the panel; he might have been listening to what had been said in the library, waited for them to get through the moving stone, and then gone on down to the crypt. Well, he couldn't get out through the tomb, in any case, Michael reflected.
He reached the stone, and set his shoulders to it. It was dangerous work, for the Monk might even then be lying in wait to shoot down his pursuers. He stayed for a moment, with a leg over the barrier, and his torch lighting up the stairs. He could see nothing, but below him he thought he heard a rustle. He sprang through and went on down. There was no sign of life in the low passage that led at the foot of the stairs to the crypt, and no glimmer of light shone in the crypt itself. He reached it, and his torch flashed round, searching every corner.
The crypt was empty. He sprang for the iron ladder, scrambled up, and shouted: "All right there? No one tried to get out?"
The men outside answered: "All right here, sir."
He climbed down again. There must be another way out, and like a blundering fool he had allowed the Monk to escape.
He heard Sergeant Matthews' voice echoing down the passage: "Where are you, sir? Mr. Draycott! Where are you?"
"Here!" Michael called, and in a few minutes the sergeant came hurrying into the crypt.
"Has he got away, sir? We got the others. The inspector's gorn up to be sure he hasn't forced that panel at the top of the stairs. Lord, this is bad luck, ain't it, sir?"
Michael was searching the crypt for any sign of an entrance. Suddenly he stopped, his torch-light turned full on to one of the coffins. It was the coffin they had looked into that morning. Then the lid had lain beside it. But now the lid covered it.
The light swept on. Michael said: "He's not here. We'd better get back to the library. Just a moment though: I'll make sure there's nothing behind these stairs."
To the sergeant's astonishment instead of going to the block staircase he pulled a note-book and a pencil from his pocket, scrawled rapidly, and then said: "Come over here and look, sergeant."
The sergeant opened his mouth, saw Michael scowl at him, and shut it again. He went to him, and Michael thrust the open book into his hands. Just sound this wall," he said, proceeding to do so.
The sergeant's puzzled eyes read: "He's in the coffin. If we lift the lid one of us'll get shot. Pretend to go away; take shoes off in passage, creep back, crouch down at head and foot of coffin, and wait for lid to lift. Then collar him as he gets out."
"No, there's nothing here," Michael said loudly. "He's gone the other way. No use keeping those two up there by the tomb. I'll send them off to search the grounds."
The sergeant's wits worked slowly but surely. "Right, sir: I'll give the word to them." He stepped under the hollow tomb, and setting his hands to his mouth shouted: "He's got away. Search the grounds!"
"Come on then!" Michael said. "We've no time to lose."
Together they went back into the passage, and along it for some yards. At a sign from Michael the sergeant stopped and began to take off his boots. In another moment they stood up in their stockinged feet, and began to creep back to the crypt.
Michael had to take the risk of a light being seen inside the coffin; he turned his torch on for just long enough to locate the coffin. Then the light disappeared again, and in the dense darkness they went up to the coffin, and crouched down at each end.
Not a sound broke the stillness. Michael set his teeth, and tried to think what he would do if no one were in this coffin.
A creak almost made him start. The coffin lid was lifting. He stayed, ready to spring. The sound of a scrape and a thud told him that the lid had been lowered to the floor of the crypt. He heard a noise as of a body moving in the coffin; he rose stealthily. He was so near the coffin that he felt some rough material brush his cheek as he got up. It gave him the position of the Monk, and he made his spring. "Light, sergeant!" he shouted.