And so he worked. Through the night, and the day, and the night after that, until his fingers burned and his eyes dimmed. He slept sparsely, catching an hour's sleep here and there, but for the most part the days and nights moved like a witching haze, the air around twisting like ivy around him, the world spinning without him anchored to the floor.
The stranger had the most majestic of plans, ornate in craft and conceived brilliantly on the scrap of yellowing paper he had handed to Mueller. "But friend, why do you need this?" He had asked, pouring over the specifications with the eye of an enthralled student, rather than the master the stranger claimed he was. "What purpose does it serve?"
The stranger smiled at the question with his thin lips, twisting at the corners like a cat in the night. "Because it is required in the world. A doorway. But the door itself will come later. I have plans for the door, don't you worry."
"I do worry. Constantly. A character flaw, I'm afraid, one I work to remove from my repertoire but consistenty fail at. But if you have plans, who am I to question them?"
"Precisely," the stranger had replied, and it did not make Mueller feel comfortable. Not one bit.
A month went by. And by the end of the month, with the wood carved to perfection, the only tarnish the blood Mueller had spilt in it's creation, the doorway was complete. Mueller couldn't help but impressed by his work. The way the frame twisted and wrended around itself was astonishing-- Mueller would not have believed himself capable of the work if he had not carved it with his own two hands. The ornate carvings he had been directed to introduce folded in on themselves, and if Mueller had an eye for ancient languages he would have read the true reason the frame was built. But he did not, and his ignorance, whilst blissful, did not last long.
"It is beautiful," said the stranger, when he arrived holding a small basket, a chequered blanket obscuring the contents. "Truly, a work of a master."
"So you say. When will the door be introduced? I would wish to be present, to make sure everything fits."
"It will fit. The dimensions of the door itself are..." The stranger considered the words, and then smiled as he settled. "Fluid."
"And what do you mean by that?" asked Mueller, tentatively.
"Ah, to tell, but to show..." said the stranger, slowly peeling off the blanket on top of his basket. "Close your eyes."