surrendering his ticket stub and false papers to the Lhari and Mentorian interpreter who guarded the ramp.

The Lhari said to the Mentorian, in the Lhari language, "Keep him for questioning but don't tell him why." Bart felt a cold chill icing his spine. This was it.

The Mentorian said briefly, "We wish to check on the proper antibody component for Aldebaran natives. There will be a delay of about thirty minutes. Will you kindly wait in this room here?"

The room was comfortable, furnished with chairs and a vision-screen with some colorful story moving on it, small bright figures in capes, curious beasts racing across an unusual veldt; but Bart paced the floor restlessly. There were two doors in the room. Through one of them, he had been admitted; he could see, through the glass door, the silhouette of the Mentorian outside. The other door was opaque, and marked in large letters: