ened, cloaked in invisibility, toward the Arvanian
Embassy--and the plans that spelled America's destruction if they
remained in Arvanian hands.

The embassy building was a three-storied oblong house of white stone
topping a terrace that started its climb from the sidewalk of Sixteenth
Street. The doors at the head of the wide stone staircase were of
bronze; and they were closed, and, Thorn surmised, efficiently barred.
The windows at front and sides were also closed, in spite of the warmth
of the sunny spring afternoon.

Beside the building, leading up in a short steep hill, was the driveway.
Up this Thorn started. The front of the house was hopelessly barred; but
at the rear entrance there might be a chance.

Up the driveway, then, he walked, a little startled at the fact that he
cast no shadow--feeling as a ghost might feel. The pavement was hot to
his thinly filmed feet. A little dubious as to the effect of heat on the
vital shell that hid him, he stepped off into the cool grass beside the
drive; and came soon to the rear of the embassy.

There was no porch or veranda, simply two stone steps leading up to a
stout oak door which opened onto the embassy kitchens. From behind this
door came the sound of crockery and the hum of voices. The Arvanian chef
evidently was preparing afternoon tea.

* * * * *

Walking boldly to the very steps, Thorn began the vigil that should end
when someone came in or out of that door, allowing him to slip inside
the building before the portal was barred shut again.

For nearly half an hour Thorn stood there before something happened that
at once helped him, and, at the same time, nearly proved his undoing.

A light delivery van sped up the driveway. The wheels stirred up a cloud
of dust. It was a very small cloud of very fine dust. Thorn at first
thought nothing of it, because he was so engrossed in the conviction
that here ought to be provided an entrance into the house.

The truck driver got out, took a crate from the body of the van, and
went with it to the back door. After a moment of waiting, the door
opened. Thorn noticed that it was opened very cautiously, only an inch
or so. He caught a glimpse of a heavy chain stretched across the inch
opening, and saw a strip of bearded, resolute face.

The door was unchained. The driver walked in, while the door stood open.
Thorn started to glide in after him....

Mere chance made him glance at a window