By the time the echo from the first knock on his door rebounded off the back of his cabin, Captain Charles Urquhart was fully awake. A lifetime at sea had given him the reflexes of a cat. By the second knock he knew through the vibrations transmitted by his mattress that the ship’s engines had been shut down, but the hiss of water flowing along her steel hull told him the Mohican had not yet begun to slow. Dishwater-colored light leaked around the curtain pulled over the room’s single porthole. With the ship heading north and his cabin on the starboard side, Urquhart estimated it was coming up on nine in the evening.

He’d been asleep less than a half hour, following a grueling twenty hours on duty as the cargo vessel ran through the tail end of an early-season hurricane.

“Come,” he called and swung his legs off his cot. The deck was covered with a carpet of such thin pile that he could feel the cool of the metal plates beneath it.

The cabin door creaked open, light from a gas lantern marking a wedge across the threshold. The ship had an electrical generator, but the few lights it powered were reserved for the bridge. “Sorry to bother, sir,” said the third officer, a Welshman named Jones.

“What is it?” Urquhart asked, the last vestiges of sleep sloughing off. No one woke the captain unless it was an emergency, and he knew he had to be ready for anything.

The man hesitated for a second, then said, “We’re not sure. We need you on the bridge.” He paused again. “Sir.”

Urquhart tossed aside his bedcovers. He thrust his feet into a pair of rubber boots and threw a ratty robe over his shoulders. A Greek fisherman’s cap finished his ridiculous outfit. “Let’s go.”

The bridge was one deck above his cabin. A helmsman stood mutely behind the large oaken wheel, his gaze not over the bow as it should have been but fixated out the port door leading to the ship’s stubby bridge wing. Urquhart followed the gaze, and although his expression didn’t change, his mind whirled.

About two miles away, an eerie blue glow clung to the horizon and blotted out the dying rays of the setting sun. It wasn’t the color of lightning or St. Elmo’s fire, which had been the captain’s first suspicion. It was a deeper blue, and a color he had never seen before.