A classic thriller from the bestselling master of action and suspense. The atomic submarine Dolphin has impossible orders: to sail beneath the ice floes of the Arctic Ocean, and somehow locate and rescue the men of weather-station Zebra, gutted by fire and drifting with the ice-pack somewhere north of the Arctic Circle.   But the orders do not say what the Dolphin will find if she succeeds that the fire at Ice Station Zebra was sabotage, and that one of the survivors is a killer.