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 to 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...