"_Polaris_ unit reporting, sir," said Tom.

"Where is Professor Sykes?" demanded Vidac abruptly without even
acknowledging the salute.

"Why, I--I don't know, sir," replied Tom.

"How about you, Manning? Astro?" asked Vidac, turning to the other
cadets. "You have anything to say?"

"We only heard about it ten minutes ago, sir," volunteered Roger.

"I'll bet!" snapped Vidac. He got up and stepped around his desk to face
the cadets. "You three were the last ones to be seen with the professor.
What happened last night?"

"We finished the study spools and left him in the office, sir," said
Tom. "Then we went for a swim in the pool and had a bite to eat before
hitting the sack. That's all."

"Did anyone see you in the pool?" asked Vidac.

"I doubt it, sir. We didn't notice anyone around," said Astro. "It was
pretty late."

"Did anyone see you at the mess hall when you went to get a bite?"
pursued Vidac. "Surely there must be someone who can substantiate your
story."