I trudged up the hill behind Haley. The sled she pulled behind her was hardly recognisable as the twenty-dollar plastic toboggan it had once been.

“And you really think this is going to work?” I asked.

“I’m sure it will. As long as you pack the snow first, so I can build up enough speed by the time I hit the ramp.”

I sighed. My little sister had been in the garage for days—no, weeks—modifying her sled, only leaving off to go to school and eat meals. The floor was strewn with papers—fiendish-looking equations, diagrams, and sketches.

Mom and Dad humored her—let her use all the power tools, bought her sheet metal, wire, and who knows what else.

“We don’t want to squash her creativity,” said Mom.

It was creative, all right. The cheap plastic sled now looked like a silver bullet, with a sleek shell over the top. A small Perspex window gave the rider some visibility out the front. Fins and wings stuck out along the sides and back.

We reached the top of the hill and I handed Haley her bike helmet.

“Mom says you have to wear this.” Haley rolled her eyes but snapped the helmet on.

“If this ruins my weight calculations…”

“Better than ruining your head,” I said.

“Help me in.”

I lifted Haley and lowered her gently through the sled’s hatch. She grinned and gave me a thumbs-up before closing the hatch behind her.

Plopping my sled down at the top of the slope, I started down the hill. I hit the ramp at a good clip and soared into the air before landing with a thud in the snow beyond.

I had only just stopped and turned when Haley began her descent. God, she was moving fast! What had she done to her sled to make it go like that? I could see her face through the window, tense and full of excitement.

She hit the ramp and seemed to go straight up. And up. And up.

Then she was gone.

I blinked at the overcast sky and waited.

A few flakes of snow spiralled lazily down.

A crow cawed from a nearby tree.

Then I went home.