Meanwhile Lieutenant Woodward and his friend had moved to a corner of the veranda and stood looking intently into the moonlight. There was Del Mar deep in conversation with a man who had slipped out, at a quiet signal, from his hiding-place in the shrubbery.
"That fellow is up to something, mark my words," muttered Arnold under his breath. "I'd like to make an arrest, but I've got to have some proof."
They continued watching Del Mar but, so far at least, he did nothing that would have furnished them any evidence of anything.
So the party went on, most merrily until, long after the guests had left, Elaine sat in her dressing-gown up in her room, about to retire.
Her maid had left her and she picked up the slip of paper from her dresser, looking at it thoughtfully.
"What can a crude drawing of a sunrise on the sea mean?" she asked herself.
For a long time she studied the paper, thinking it over. At last an idea came to her.
"I'll bet I have it," she exclaimed to herself. "Something is going to happen on the water at sunrise."
She took a pretty little alarm clock from the table, set it, and placed it near her bed.
Returning from the party to his library, Del Mar entered. Except for the moonlight streaming in through the windows the room was dark. He turned on the lights and crossed to the panel in the wall. As he touched a button the panel opened. Del Mar switched off the lights and went through the panel, closing it.