column told of the arrest of many Germans all over the country, men who
were suspected of caring more for the Fatherland than they did for the
United States.

There was no mention of the bomb episode on the railroad bridge the night
before, however. Bob knew that the authorities would not permit the
publication of any such items if they could prevent it so he was not
surprised. Presently the rest of the family appeared and they went in to
breakfast.

Mr. Cook's mail was lying on the table by his plate; it was his custom
every morning to glance it over while he was eating. While Mrs. Cook
talked to Bob about Harold, her husband looked through his letters.
Suddenly he uttered an exclamation of surprise. "Here's a queer
thing," he said.

"What?" demanded Mrs. Cook anxiously. She had been very nervous lately.

"This postcard," said Mr. Cook. "Listen to what it says. 'Take the advice
of one who knows and keep your automobile home at night.'"

Bob turned pale. "What does it mean!" inquired Mrs. Cook.

"I'm sure I don't know," said her husband.

"How is it signed?"

"It is not signed at all."

"I can't imagine what it's all about," said Mr. Cook. "As far as I know,