One of the branches disappeared.

I gave a little gasp and straightened, and suddenly the branch was there again.

“You okay, Mom?” Bess said.

I didn’t reply. Instead, keeping my eye on the branch, I bent again and…slowly it faded from view.

“Oh, dear God! Something’s wrong with that thing!”

Bess stepped to my side.

“What do you—holy shit!” Obviously she’d seen it too. She stepped back. “Ohmigod, the whole top just disappeared. Ellie, do you see this?”

“Uh, huh. It’s all a matter of getting the geometry just right.”

Bess moved again. “Now the top’s back but the whole left side is gone! Ellie, what the fuck!”

“Bess!” I said, but I knew how she felt. What the fuck indeed.

“Nothing’s actually gone,” Ellie said, keeping her eyes fixed on the lower part of the construction. “It simply angles into another place.”

“‘Another place’?” Bess’s eyes were wide. “What does that even mean? Another plane of existence, another dimension, the other side of the wall, what?”

Ellie shrugged. “Yeah, I guess so. Sort of.”

“‘Sort of’? Wh-wh-wh-wh—” Bess sounded like a stuck record.

And then I felt a warm breeze against my shins. It flowed from under the bed. No, it came from the pile, from the arch at its base, and flowed under the bed.

And the arch…the opening was dark now. Where I used to be able to see the floor molding and some of the bedroom wall…only blackness now.

“Oh, excellent!” Ellie said. “I did get it right.”

Get what right? I wanted to say, but couldn’t take my eyes off that dark space.

Ellie dropped to her hands and knees. “Okay, I’m going in.”

“Going in where?” Bess said with a laugh. “There’s no place to go.”

“Sure there is. See you later.”

With that she crawled through the arch and disappeared inside.

“Ellie!” I cried. “Ellie, don’t.”

Her voice, strangely distorted, echoed back about being by herself.

Bess wasn’t laughing anymore. “That’s impossible! Mom, she can’t—don’t let her go!” She dropped to her knees beside the arch and reached inside to grab Ellie’s foot or leg but came away with nothing. “Mom, she’s gone! But she can’t be gone! It’s not possible!”

My brain was numb but I knew what she meant.

Ellie’s construction lay against an outside wall. A hole in the wall could lead only to empty outside air. Yet Ellie had crawled all the way through and beyond. I rushed to the window and looked out. The outer wall was unmarred. Nothing extended beyond it.

I dropped beside Bess and stuck my head inside. Warm, odorless air flowed against my face.

“Ellie? Ellie! You come back here! You come back here this instant!”

Faintly, as if from a great distance, I heard, “…fine…little while…myself.”

Bess fumbled with her key chain and came up with a pen light. Aimed through the arch, its bright beam lit up a long, narrow passage with rippled-ribbed walls of gleaming black. Bright as it was, the beam didn’t reach the end.