The turquoise hull of the Narwhal came into view, and Giordino drove slightly past the vessel, parking the truck next to a building marked HARBORMASTER’S OFFICE. He returned the keys to the borrowed truck inside, then helped Pitt with his bags. Captain Stenseth and Jack Dahlgren were quick to greet Pitt as he boarded the NUMA ship.

“Did Loren finally take a rolling pin to your noggin?” Dahlgren asked, spotting the bandage on Pitt’s head.

“Not yet. Just a result of some poor driving on my part,” he answered, brushing aside the concern.

The men sat down in a small lounge near the galley as cups of hot coffee were distributed to all. Dahlgren proceeded to brief Pitt on the abbreviated discovery of the thermal vent while Stenseth discussed the rescue of the Canadian ice lab survivors.

“What’s the local speculation on who could have been responsible?” Pitt asked.

“Since the survivor’s description perfectly matches that of our frigate the Ford, everyone thinks it was the Navy. We’ve been told, of course, that she was three hundred miles away at the time,” Giordino said.

“What no one seems to consider is that there are very few active icebreakers up here,” Stenseth said. “Unless it was a rogue freighter risking its own skin or foolishly off course, the potential culprits are relatively small in number.”

“ The only known American icebreaker in these waters is the Polar Dawn,” Giordino said.

“Make that a Canadian icebreaker now,” Dahlgren said, shaking his head.

“She doesn’t match the description anyway,” Stenseth said. “Which leaves a handful of Canadian military vessels, the Athabasca escort ships, or a foreign icebreaker, possibly Danish or even Russian.”

“Do you think it was a Canadian warship that struck the camp by accident and they are trying to cover it up?” Pitt asked.

“One of the scientists, Bue was his name, swears he saw an American flag, in addition to the hull number that matches the Ford,” Dahlgren said.

“It doesn’t figure,” Giordino said. “The Canadian military wouldn’t try to instigate a conflict by masquerading as an American warship.”

“What about these Athabasca escort ships?” Pitt asked.

“By Canadian law, all commercial traffic through ice-clogged sections of the Northwest Passage requires an icebreaker escort,” Stenseth said. “A private firm, Athabasca Shipping, handles the escort duty. They operate a number of large icebreaker tugs, which are also used to haul their fleet of oceangoing barges. We saw one towing a string of enormous liquid-natural-gas barges passing through the Bering Strait a few weeks ago.”

Pitt’s eyes lit up. He opened a briefcase and pulled out a photograph of a massive barge under construction in New Orleans. He handed the picture to Stenseth.

“Any resemblance to this one?” Pitt asked.

Stenseth looked at the photo and nodded. “Yes, it’s positively the same type. You don’t see barges of that size very often. What’s the significance?”