“Well, if that’s your opinion, what’s best to be done Sergeant?  I agree that the Child of Kings should not be told, and I shan’t leave this place till after ten o’clock to-night at the earliest, if we stick to our plans, as we had better do, for all that stuff in the tunnel wants a little time to settle, and for other reasons.  What are you drawing there?” and he pointed to the floor, in the dust of which Quick was tracing something with his finger.

“A plan of our Lady’s private rooms, Captain.  She told you she was going to rest at sundown, didn’t she, or earlier, for she was up most of last night, and wanted to get a few hours’ sleep before—­something happens.  Well, her bed-chamber is there, isn’t it? and another before it, in which her maids sleep, and nothing behind except a high wall and a ditch which cannot be climbed.”

“That’s quite true,” interrupted Higgs.  “I got leave to make a plan of the palace, only there is a passage six feet wide and twenty long leading from the guard chamber to the ladies’ anteroom.”

“Just so, Professor, and that passage has a turn in it, if I remember right, so that two well-armed men could hold it against quite a lot.  Supposing now that you and I, Professor, should go and take a nap in that guard-room, which will be empty, for the watch is set at the palace gate.  We shan’t be wanted here, since if the Captain can’t touch off that mine, no one can, with the Doctor to help him just in case anything goes wrong, and Japhet guarding the line.  I daresay there’s nothing in this yarn, but who knows?  There might be, and then we should blame ourselves.  What do you say, Professor?”

“I?  Oh, I’ll do anything you wish, though I should rather have liked to climb the cliff and watch what happens.”

“You’d see nothing, Higgs,” interrupted Oliver, “except perhaps the reflection of a flash in the sky; so, if you don’t mind, I wish you would go with the Sergeant.  Somehow, although I am quite certain that we ought not to alarm Maqueda, I am not easy about her, and if you two fellows were there, I should know she was all right, and it would be a weight off my mind.”

“That settles it,” said Higgs; “we’ll be off presently.  Look here, give us that portable telephone, which is of no use anywhere else now.  The wire will reach to the palace, and if the machine works all right we can talk to you and tell each other how things are going on.”

Ten minutes later they had made their preparations.  Quick stepped up to Oliver and stood at attention, saying: 

“Ready to march.  Any more orders, Captain?”

“I think not, Sergeant,” he answered, lifting his eyes from the little batteries that he was watching as though they were live things.  “You know the arrangements.  At ten o’clock—­that is about two hours hence—­I touch this switch.  Whatever happens it must not be done before, for fear lest the Doctor’s son should not have left the idol, to say nothing of all the other poor beggars.  The spies say that the marriage feast will not be celebrated until at least three hours after moonrise.”