A half-successful debut that comes to life only when storms rage over Lake Superior. Harry Potter disappears aboard his sailboat when a storm blows up, leaving behind a distraught wife; a woman on the rampage--Big Charlie, whom Harry swindled out of the gold from an illegal mining venture; and a dead man, logger Carl Hoffman, Big Charlie's lover and the third member of the gold-mining operation. Sheriff Ray MacNulty and his deputy Walt focus on the murder, but get hints that Potter may have staged his own disappearance and may, in fact, be sailing down Mobile way with his boat's bilge laden with gold. When they finally catch up with Potter, he implicates Big Charlie, and their confrontation culminates in a shot, a dynamite blast, and a conflagration--but no charred bones to identify either Potter or Big Charlie. Another of Potter's set-ups? Was Big Charlie a duped partner or a loving sidekick? A postcard to MacNulty's office soon illuminates. Tricky plot turns, but flat prose. Weekend sailors, however, may savor the boating know-how.