Excerpt
The Harn first came to the Warden's attention through its effect on the game population of an area in World 7 of the Warden's sector. A natural ecology was being maintained on World 7 as a control for experimental seedings of intelligent life-forms in other similar worlds. How the Harn got there, the Warden never knew. In its free-moving larval state, the Harn was a ticklike creature which might have sifted through a natural inter-dimensional rift; or it might have come through as a hitchhiker on some legitimate traveler, possibly even the Warden himself.
In any event, it was there now. Free of natural enemies and competition, it had expanded enormously. So far, the effect in the control world was localized, but this would not be the case when the Harn seeded. Prompt action was indicated.
The Warden's inclination and training was in the direction of avoiding direct intervention in the ecology of the worlds under his jurisdiction, even in the field of predator control. He considered introduction of natural enemies of the Harn from its own world, and decided against it. That cure was as bad, if not worse, than the disease itself.
There was, however, in one adjacent world, a life-form not normally associated with the Harn; but which analysis indicated would be inimical to it, and reasonably amenable to control.
It was worth trying, anyway.
October 3rd, Ed Brown got up to the base cabin of his trap line with his winter's outfit.
He hung an N. C. Company calendar on the wall and started marking off the days.
October 8th, the hole into the other world opened.
In the meantime, of course, Ed had not been idle. All summer the cabin had stood empty. He got his bedding, stove, and other cabin gear down from the cache and made the place livable. The mice were thick, a good fur sign, but a nuisance otherwise. Down in the cellar hole, when he went to clear it out for the new spud crop, he found burrowings everywhere.
Well, old Tom would take care of that in short order. Tom was a big, black, bobtailed cat eleven years old who had lived with Ed since he was a kitten. Not having any feline companionship to distract him, his only interest was hunting mice. Generally he killed a lot more than he could eat, racking the surplus in neat piles beside the trail, on the doorstep, or on a slab in the cellar. He was the best mouser in interior Alaska.
Ed propped the cellar hatch with a stick so old Tom could come and go as he pleased, and went on about his chores, working with a methodical efficiency that matched Tom's and went with his thinning gray hair and forty years in the woods. He dug the spuds he had planted that spring. He made a swing around his beaver lakes, tallying the blankets in each house. He took the canoe and moved supplies to his upper cabin. He harvested some fat mallards that had moved down on the river with the coming of skim ice on the lakes. He bucked up firewood and stacked it to move into camp with the first snow.
On the fifth morning, as he was going down to the boat landing with a pail for water, he found the hole into the other world.
Ed had never seen a hole into another world, of course, nor even heard of such a thing. He was as surprised as any one would naturally be to find one not fifty feet from their front door.
Still, his experience had been all in the direction of believing what his eyes told him. He had seen a lot of strange things in his life, and one more didn't strain him too much. He stood stockstill where he had first noticed the hole and studied it warily.
It was two steps off the trail to the left, right beside the old leaning birch, a rectangular piece of scenery that did not fit....