“Of course he couldn’t work in daylight. Most of the night after his disappearance the lagoon was guarded. Yet it isn’t easy to see why he didn’t make the attempt the night of his disappearance——”
“I suppose he was waiting for a favorable time. He had to have certain equipment, I suppose—to keep from being carried down. Perhaps there are certain periods when the flow through the channel is less, and there isn’t so much suction——”
A sudden light in the girl’s face arrested me and held me. Her eyes were sparkling like blue seas in the sunlight. “‘At F. T.,’” she quoted. “Ned, Ned, what stupids we are! Don’t you see——”
“I can’t say that I do. I saw ‘At F. T.,’ at the bottom of the script, but I don’t know what it meant——”
“‘At flood tide’—that’s what it meant! Just as a sailor would say it. He told on his own directions the way to safety. When the tide flows the water movement is probably in the other direction through the underground channel, and the lagoon is as safe as a lake; and it’s only in the ebb-tide that the suction exists. And of course the ignorant treasure-seeker would make his search in the ebb-tide, when the surface of the lagoon is still.”
Exultant over this, a discovery that, if the treasure was a reality, assured its procurance, neither of us noticed the dignified, courteous approach of Pescini from the hallway. He was distinguished as ever, his dinner-jacket unruffled, his linen gleaming white in the dying light.
“Have you seen Sheriff Slatterly anywhere?” he asked me. “I’m in a sort of quandary—I’ve got a letter on my hands and don’t know what to do with it.”
“A letter?” I repeated. The skin was twitching on my back.
“Yes. I hardly know whether to send it on—or whether he will want it for the investigations. It’s one that Major Dell gave me a few days ago to mail, but which I dropped in my pocket and forgot.”