"Yes," said Calhoun. "I know about it. I helped design it. I want to
explain it to the admiral. He needs to know what's happened, if he's to
take appropriate measures."

There were jitterings. Many men in sag-suits had still no idea that
anything had gone wrong. Some appeared, brightly carrying loot. Some
hung eagerly around the airlocks of ships on the grid tarmac, waiting
their turns to stand in corrosive gases for the decontamination of their
suits, when they would burn the outer layers and step, aseptic and
happy, into a Wealdian ship again. There they could think how rich they
were going to be back on Weald.

But the situation aloft was bewildering and very, very ominous. There
was strident argument. Presently Calhoun stood before the Wealdian
admiral.

"I came to explain something," said Calhoun pleasantly. "The situation
has changed. You've noticed it, I'm sure."

The admiral glared at him through two layers of plastic, which covered
him almost like a gift-wrapped parcel.

"Be quick!" he rasped.

"First," said Calhoun, "there are no more blueskins. An epidemic of
something or other has made the blue patches on the skins of Darians
fade out. There have always been some who didn't have blue patches. Now
nobody has them."

"Nonsense!" rasped the admiral. "And what has that got to do with this
situation?"

"Why, everything," said Calhoun mildly. "It means that Darians can pass
for Wealdians whenever they please. That they are passing for Wealdians.
That they've been mixing with your men, wearing sag-suits exactly like
the one you're wearing now. They've been going aboard your ships in the
confusion of returning looters. There's not a ship now aloft, that has
been aground today, that hasn't from one to fifteen Darians--no longer
blueskins--on board."

The admiral roared. Then his face turned gray.

"You can't take your fleet back to Weald," said Calhoun gently, "if you
believe its crews have been exposed to carriers of the Dara plague. You
wouldn't be allowed to land, anyhow."

The admiral said through stiff lips;

"I'll blast--"

"No," said Calhoun, again gently. "When you ordered all ships alerted
for action, the Darians on each ship released panic-gas. They only
needed tiny, pocket-sized containers of the gas for the job. They had
them. They only needed to use air-tanks from their sag-suits to protect
themselves against the gas. They kept them handy. On nearly all your
ships aloft your crews ar