The Mystery of Swordfish Reef

One calm October day three men set out from Bermagui harbour in a fishing launch and disappeared into the rippleless Tasman Sea. Then the head of one of them, riddled with bullets, is brought up in a ship's trawl--it belonged to Ericson, formerly one of the Big Five at Scotland Yard. Why had he been shot and thrown overboard? Who had killed him? And where were the launchman and his mate? The bush had never defeated Bony but there were no clues in the sepulchre of the sea.