Half-way along the main corridor was a large room, whose steel walls were masked by tapestries, where renters could examine their treasures on marble tables. It was empty when Simon went in. The patrol carefully closed the door on him, and then in a moment came back to say that Mr.

Brown was not in his office, and had probably gone out to lunch, the hour being noon.

'Where did you see Mr. Hugo?' Simon asked, hurrying out of the room in a state of considerable agitation.

'I saw him just here, sir,' said the patrol, turning down a short side corridor--the grille was unfastened--and stopping before a door numbered thirty-nine. 'He was talking to Mr. Brown, and the door of the vault was open.'

'That must be Mr. Polycarp's vault,' Simon observed; and then he started, and put his ear against the door. 'Listen!' he exclaimed to the patrol. 'Can't you hear anything inside?'

And the patrol also put his ear to the steel face of the door.

'I seem to hear a faint knocking, but it's that faint as you scarcely _can_ hear it. There! it's stopped.'

'He is inside,' Shawn whispered.

'Who's inside?'

'Mr. Hugo.'

'It's G.o.d help him, then,' said the patrol, 'if he's there long. There's no ventilation, Mr. Shawn. We'd better telephone for Mr. Polycarp. The other key will be in the key-safe. I can get it. But how do you make out, sir, that Mr. Hugo can be in there? The vault could only be locked by Mr. Polycarp and Mr. Brown together, and surely they couldn't both--'

'Mr. Polycarp left his keys behind by accident. He had gone before Mr.

Hugo came down.'

'There's been no Mr. Polycarp here this morning,' said the patrol a minute later. 'I've looked at the signature-book. I thought it was queer I hadn't seen him. And, what's more, that isn't Mr. Polycarp's vault at all. Mr. Polycarp's vault is No. 37. This vault has been empty for several weeks.'

'Then you have both the keys?' Simon demanded quickly.

'No, sir. It's very strange. There's only one key of No. 39 in the key-safe, and it's the renter's key.'

'Then Mr. Brown must have the other.'

'I expect so. But he ought not to have. It's against rules,' said the patrol. 'I know where he takes his lunch. I'll send for him.'

Simon put his ear again to the face of the door. The faint knocking had ceased, but after a few seconds it recommenced.

'And suppose you don't find Mr. Brown?' he queried, still listening.

'Then that vault can't be opened. But never you fear, Mr. Shawn. I'll have him here in three minutes. It's funny as he should have left anybody in there by accident--and Mr. Hugo of all people in this blessed world....'

The patrol's accents died away as he pa.s.sed down the main corridor.

Within the next half-hour Simon, who had the rare virtue of being honest with himself, was freely admitting, in the privacy of his own mind, that the crisis had got beyond his power to grapple with it, and he had begun to fear complications more dreadful than he dared to put into words. For the patrol had failed to find Mr. Brown. Mr. Brown, head guardian of the Safe Deposit, had disappeared. Nor was this all. A renter had come to take his belongings from a safe in the third side-pa.s.sage on the left, and the sub-guardian imprisoned in that pa.s.sage could not open the grille between it and the main corridor. He had his key, but the key would not turn in the glittering lock. The renter, too impatient to wait, had departed very angrily at this excess of safety. Then it was gradually discovered that every sub-guardian in every side-pa.s.sage was similarly imprisoned. Not a key in the entire place would turn. The patrol rushed to the main door. The three keys had clearly been turned while the door was opened, and the shot bolts prevented the door from closing. This explained why the door was ajar, but it did not explain the absence of the doorkeeper, who had apparently followed in the footsteps of his chief, Mr. Brown.

'The time-lock! Someone must have set it!' cried the patrol to Shawn, and the two hastened to the other end of the main corridor, where the dial of the machine glistened under an electric lamp.

And all the sub-guardians stirred and grumbled in their beautiful bright cages like wrathful lions. No such scene had ever been known in that Safe Deposit or any other safe deposit before.

The patrol was right. The dial of the time-lock showed that it had been set against every lock, great and small, in the Safe Deposit, until nine a.m. the next day.

'It's all up!' the patrol said solemnly.

'Do you mean to say nothing can be done to open that vault till nine to-morrow?' Simon demanded in despair.

'Nothing. The blooming Czar couldn't manage it with all his Cossacks!

No, nor Bobs either! This is a Safe Deposit, this is, and if Mr. Hugo is in that vault, it's Mr. Hugo as knows it's a Safe Deposit by now.'

A brief silence ensued, and then Simon said:

'We must telephone to the police. There's a telephone in the waiting-room, isn't there?'

The patrol admitted that there was, but his manner hinted a low opinion of the utility of the police. He stood mute while Simon Shawn told the telephone receiver what had occurred in the bowels of the earth beneath Hugo's.

'Wait a minute,' said the telephone, and then, after a pause: 'Are you there? I'm Inspector Winter.'

'That's him as has charge of all the strong-room cases,' the patrol interjected to Simon.

'I've got Mr. Jack Galpin here, as it happens,' said the telephone.

'Mr. Jack Galpin?' Simon questioned.

'He's just done eighteen months for an attempt in Lombard Street,' the patrol explained. 'I've heard of him.'

'I'll come down with him immediately in a cab,' said the telephone.

When Simon returned to the impregnable door of Vault 39 he listened in vain for a sound. Then he knocked with his pen-knife on the polished steel, and presently there was an answering signal from within--a series of scarcely perceptible irregular taps. It struck him that the irregularity of the taps formed a rhythm, and after a few seconds he recognised the rhythm of the Intermezzo from 'Cavalleria Rusticana,'

which he had played for Hugo that very morning.

It was at this moment that the messenger-boy attached to the department came whistling into the steel corridors, and delivered to the patrol a small white packet, which, he said, Mr. Brown had handed to him with instructions to hand it to the patrol. He had seen Mr. Brown in a cab outside the building, and Mr. Brown had the appearance of being very ill.

The packet contained the second key of Vault 39.

'But this'll be no use till to-morrow,' was the patrol's comment, 'and by then--'

CHAPTER XIII

MR. GALPIN

When the patrol and Simon between them had explained the mysterious and fatal situation to Mr. Jack Galpin, Mr. Jack Galpin leaned against one of the marble tables in the waiting-room, and roared with laughter.

'Well,' observed Mr. Galpin, 'he didn't have his Safe Deposit built for nothing, anyhow!'

And he laughed again.

'But he's slowly dying in there!' said Simon.