ERSKINE POWELL OF SCOTLAND YARD IS BACK--INVESTIGATING THE STRANGE RIDDLE OF PENRICK SANDS. On the north coast of Cornwall, residents in the quaint seaside town of Penrick report a terrifying phenomenon--an eerie, glowing apparition that rides the surf at night, adding a weird fascination to this place of picturesque streets, secluded beaches, and abandoned mines. Yet Chief Superintendent Powell soon learns that Penrick already harbors unsolved mysteries. For, thirty years ago, someone killed a teenager and left her body to wash up on Penrick Sands--precisely where the apparition now appears. In fact, Powell faces not one but two strangely intertwined puzzles and a double-edged sword of menace. . . .