Finally came a soft tapping on the hidden door behind Woodhouse. The latter heard the doctor exchange whispers with the Numidian in the hallway. Finally, "Show him into the waiting-room," Koch ordered. He came back to where the captain was sitting, a puzzled frown between his eyes.

"An Englishman, Caesar says--an Englishman, who insists on seeing me--very important." Koch bit the end of one stubby thumb in hurried thought. He suddenly whipped open the door of one of the instrument cases, pulled out a stethoscope, and hooked the two little black receivers into his ears. Then he turned to Woodhouse.

"Quick! Off with your coat and open your shirt. You are a patient; I am just examining you when interrupted. This may be one of these clumsy English secret-service men, and I might need your alibi." The sound of an opening door beyond the folding doors and of footsteps in the adjoining room.

"You say you are sleepless at night?" Doctor Koch was talking English. "And you have a temperature on arising? Hm'm! This under your tongue, if you please"--he thrust a clinical thermometer between Woodhouse's lips; the latter already had his coat off, and was unbuttoning his shirt. Koch gave him a meaning glance, and disappeared between the folding doors, closing them behind him.

The captain, feeling much like a fool with the tiny glass tube sprouting from his lips, yet with all his faculties strained to alertness, awaited developments. If Doctor Koch's hazard should prove correct and this was an English secret-service man come to arrest him, wouldn't suspicion also fall on whomever was found a visitor in the German spy's house? Arrest and search; examination of his scarab pin--that would not be pleasant.

He tried to hear what was being said beyond the folding doors, but could catch nothing save the deep rumble of the doctor's occasional bass and a higher, querulous voice raised in what might be argument. Had he dared. Woodhouse would have drawn closer to the crack in the folding doors so that he could hear what was passing; every instinct of self-preservation in him made his ears yearn to dissect this murmur into sense. But if Doctor Koch should catch him eavesdropping, embarrassment fatal to his plans might follow; besides, he had a feeling that eyes he could not see--perhaps the unwinking eyes of the Numidian, avid for an excuse to put into practise his dexterity with the Bedouin dagger--were on him.

Minutes slipped by. The captain still nursed the clinical thermometer. The mumble and muttering continued to sound through the closed doors. Suddenly the high whine of the unseen visitor was raised in excitement. Came clearly through to Woodhouse's ears his passionate declaration:

"But I tell you youVe got to recognize me. My number's Nineteen Thirty-two. My ticket was stolen out of the head of my cane somewhere between Paris and Alexandria. But I got it all right--got it from the Wilhelmstrasse direct, with orders to report to Doctor Emil Koch, in Alexandria!"

Capper! Capper, who was to be betrayed to the firing squad in Malta, after his Wilhelmstrasse ticket had passed from his possession. Capper on the job!

Woodhouse hurled every foot pound of his will to hear into his ears. He caught Koch's gruff answer:

"Young man, you're talking madness. You're talking to a loyal British subject.