After a week the wind died, but the sky was clear, and in the afternoons and evenings Admiral Lacker raised the light-sail, and they ran along on the strength of a storm of sunshine. Quentin had been to the far west of Fillory, when he hunted the White Stag over the Western Sea, but the far east was a very different place. It had a polar quality. The sun was bright and hot here, but the air was getting colder. Even in the mornings, when the sun seemed dangerously close, like it was going to light the mast on fire, they could see their breath. The blue of the sky was deep and vivid. It felt like Quentin could fall up into it if he wasn’t careful.

The water was an icy aquamarine, and the Muntjac slipped through it almost frictionlessly, barely leaving a ripple. It was different stuff from ordinary seawater—silkier and less dense, with almost no surface tension, more like rubbing alcohol. Only one kind of fish lived in it, long silvery bullets that flashed and dashed through the water in diamond-shaped schools. They caught a few, but they didn’t look edible. They had huge eyes, and no mouths, and their flesh was bright white and smelled like ammonia.

The world around them began to feel thin. It was nothing Quentin could put his finger on, but the material of reality itself seemed to be getting sheer and fragile, stretched taut over its frame. You could feel the chill of the outer dark right through it. They all caught themselves moving slowly and gently, as if they might put a foot through the fabric of space-time by accident.

The sea was getting shallower too. You could see the bottom through the glassy water, and every morning when Quentin checked it, it was closer. This was an interesting phenomenon from an oceanographic point of view, but more to the point it was a problem. The Muntjac wasn’t a big ship, but it still drew twenty feet or so, and at this rate they were going to run aground long before they got to wherever the hell they were going.

“Maybe Fillory doesn’t have an End,” Quentin said one night, as they were tucking into their increasingly meager and unappetizing rations.

“What, like it’s infinite?” Josh said. “Or it’s a sphere, like Earth? God, I hope it’s not that. What if we end up back at Whitespire again? Man, I’ll be pissed if all we’ve done is find the Northwest Passage or whatever after all that.”

He licked his fingers, getting the extra salt from a salt biscuit. He was the only one who didn’t seem overawed by the situation.

“I meant more like a Möbius strip. What if it’s all one side, and no edge?”

“I think you mean a Klein bottle,” Poppy said. “A Möbius strip still has edges. Or one edge.”