Whiting set to work immediately, while Kennedy gave him the final instructions.

Neither Lane nor Miss Euston spoke a word, even when I left the room for a moment, fearing that three was a crowd.  I could not help wondering whether she might not have heard something more from the woman in the tea-room conversation than she had told us.  If she had, she had been more frank with Lane than with us.  She must have told him.  Certainly she had not told us.  It was the only way I could account for the armed truce that seemed to exist as, hour after hour, our train carried us nearer the point where we were to meet the treasure-train.

At Worcester we had still a long wait for the argosy that was causing so much anxiety and danger.  It was long after the time scheduled that we left finally, on our return journey, late at night.

Ahead of us went a dummy pilot-train to be sacrificed if any bridges or trestles were blown up or if any new attempts were made at producing artificially broken rails.  We four established ourselves as best we could in a car in the center of the treasure-train, with one of the armed guards as company.  Mile after mile we reeled off, ever southward and westward.

We must have crossed the State of Connecticut and have been approaching Long Island Sound, when suddenly the train stopped with a jerk.  Ordinarily there is nothing to grow alarmed about at the mere stopping of a train.  But this was an unusual train under unusual circumstances.

No one said a word as we peered out.  Down the track the signals seemed to show a clear road.  What was the matter?

“Look!” exclaimed Kennedy, suddenly.

Off a distance ahead I could see what looked like a long row of white fuses sticking up in the faint starlight.  From them the fresh west wind seemed to blow a thick curtain of greenish-yellow smoke which swept across the track, enveloping the engine and the forward cars and now advancing toward us like the “yellow wind” of northern China.  It seemed to spread thickly on the ground, rising scarcely more than sixteen or eighteen feet.

A moment and the cloud began to fill the air about us.  There was a paralyzing odor.  I looked about at the others, gasping and coughing.  As the cloud rolled on, inexorably increasing in density, it seemed literally to grip the lungs.

It flashed over me that already the engineer and fireman had been overcome, though not before the engineer had been able to stop the train.

As the cloud advanced, the armed guards ran from it, shouting, one now and then falling, overcome.  For the moment none of us knew what to do.  Should we run and desert the train for which we had dared so much?  To stay was death.

Quickly Kennedy pulled from his pocket the gauze arrangements he had had in his hand that morning just as Miss Euston’s knock had interrupted his conversation with me.  Hurriedly he shoved one into Miss Euston’s hands, then to Lane, then to me, and to the guard who was with us.