The young man looked upon her aghast. Then a generous current poured along his veins. `That is all one,' he said. `If you be all you say, you have the greater need of me.'

`Is it possible,' she exclaimed, `that I have schemed in vain? And will nothing drive you from this house of death?'

`Of death?' he echoed.

`Death!' she cried: `death! In that box that you have dragged about London and carried on your defenceless shoulders, sleep, at the trigger's mercy, the destroying energies of dynamite.'

`My God!' cried Harry.

`Ah!' she continued wildly, `will you flee now? At any moment you may hear the click that sounds the ruin of this building. I was sure M'Guire was wrong; this morning, before day, I flew to Zero; he confirmed my fears; I beheld you, my beloved Harry, fall a victim to my own contrivances. I knew then I loved you - Harry, will you go now? Will you not spare me this unwilling crime?'

Harry remained speechless, his eyes fixed upon the box: at last he turned to her.

`Is it,' he asked hoarsely, `an infernal machine?'

Her lips formed the word `Yes,' which her voice refused to utter.

With fearful curiosity, he drew near and bent above the box; in that still chamber, the ticking was distinctly audible; and at the measured sound, the blood flowed back upon his heart.

`For whom?' he asked.

`What matters it,' she cried, seizing him by the arm. `If you may still be saved, what matter questions?'

`God in heaven!' cried Harry. `And the Children's Hospital! At whatever cost, this damned contrivance must be stopped!'

`It cannot,' she gasped. `The power of man cannot avert the blow. But you, Harry - you, my beloved - you may still - '

And then from the box that lay so quietly in the corner, a sudden catch was audible, like the catch of a clock before it strikes the hour. For one second the two stared at each other with lifted brows and stony eyes. Then Harry, throwing one arm over his face, with the other clutched the girl to his breast and staggered against the wall.

A dull and startling thud resounded through the room; their eyes blinked against the coming horror; and still clinging together like drowning people, they fell to the floor. Then followed a prolonged and strident hissing as from the indignant pit; an offensive stench seized them by the throat; the room was filled with dense and choking fumes.

Presently these began a little to disperse: and when at length they drew themselves, all limp and shaken, to a sitting posture, the first object that greeted their vision was the box reposing uninjured in its corner, but still leaking little wreaths of vapour round the lid.

`Oh, poor Zero!' cried the girl, with a strange sobbing laugh. `Alas, poor Zero! This will break his heart!'