association with the Invincibles--her fears now identified the noble
vagabond as the writer of the anonymous letters, which had so seriously
excited her godfather's doubts of his own safety.

When Sir Giles returned, and took her with him to his house, he spoke
of his consultation with the Sergeant in terms which increased her
dread of what might happen in the future. She was a dull and silent
guest, during the interval that elapsed before it would be possible to
receive Arthur's reply. The day arrived--and the post brought no relief
to her anxieties. The next day passed without a letter. On the morning
of the fourth day, Sir Giles rose later than usual. His correspondence
was sent to him from the office, at breakfast-time. After opening one
of the letters, he dispatched a messenger in hot haste to the police.

"Look at that," he said, handing the letter to Iris. "Does the assassin
take me for a fool?"

She read the lines that follow:

"Unforeseen events force me, Sir Giles, to run a serious risk. I must
speak to you, and it must not be by daylight. My one hope of safety is
in darkness. Meet me at the first milestone, on the road to Garvan,
when the moon sets at ten o'clock to-night. No need to mention your
name. The password is: _Fidelity."_

"Do you mean to go?" Iris asked.

"Do I mean to be murdered!" Sir Giles broke out. "My dear child, do
pray try to think before you speak. The Sergeant will represent me, of
course."