In the summer of 2006, the U.S. Army Corps of Engineers sent a decrepit dredge, the M.V. *Isle Royale*, to clear the channel at Munising Bay. The crew of four — three men and a woman who ran the galley — noticed it first as a change in the water's color, then as a sound that had no origin: a low hum that vibrated through the hull at night. Then the dredge began to bring up things it shouldn't have — a woman's shoe, a wedding ring, a pocket watch stopped at 3:47. The captain was a man named Theodore Novak, who had worked the lakes for thirty years and never believed in the old stories. But by the third week, he was sleeping in the wheelhouse with a flare gun in his lap. The night the dredge returned to harbor under its own power with no one aboard, Novak was found in the mud below the anchor chain, his eyes open, his mouth full of sand. Luna pieces together what happened from the Coast Guard report and a voicemail Novak left his daughter at 3:47 in the morning — a voicemail she still hasn't deleted.