Hogan and Onyx are aboard the U.S. Coast Guard Cutter Alder as it makes its annual voyage across Lake Superior to where the SS Edmund Fitzgerald sank forty years earlier during a violent storm. As Hogan, Onyx, and the rest of the crew brave gale-force winds and freezing rain to commemorate the twenty-nine sailors who lost their lives in the 1975 tragedy, both Hogan and Onyx become ill as the Alder is tossed around in the rough waters. When Onyx suddenly collapses, the captain orders a medical evacuation and calls a Coast Guard helicopter for assistance. Hogan and Onyx are rushed to Station St. Ignace, but what the flight crew discovers when they examine Onyx will surprise everyone.