Lindsay wanted a treehouse. She explained to her dad, the carpenter, that girls need private places where they can hang out free from intrusion.

"Intrusion?" Dad asked.

"Boys," Lindsay answered. "This will be a girls-only kind of place."

"You mean like the bathroom in the morning?"

"Ohhh Daaaddy," Lindsay said with all the exasperation an 8-year-old can muster.

And so the matter was settled. But not without certain prerequisites, Dad said. First, Lindsay would have to design her treehouse, on paper, and provide him with a detailed materials list. "You can't just build something," he said. "You have to have a plan."

So Lindsay set to work. She used a ruler and big white sheets of ledger paper. She measured, she drew, she chewed on the end of her pencil for a while, she erased and drew again. Finally she was ready. Waving her "blueprints" like a banner, she sought out her father. "Let's go," she said. "It's Saturday. No time to lose."

She spread the plans on Dad's drafting table and waited expectantly. Dad looked closely at the conglomeration of lines and angles, decorated here and there with stray hearts and flowers -- quintessential Lindsay, to be sure. "Well," he began diplomatically, "what have we here?"

"This," said Lindsay, pointing proudly, "is the foyer. These French doors lead into the sunken living room. The fireplace is over there. Here's the balcony -- I'll want it left natural so it blends with the tree. The rest can be painted."

Dad took it all in stride. "What's this?" he asked.

"That's the kitchen," she said. "Eat-in. I'll want linoleum floors."

Dad stroked his chin thoughtfully. "Okay," he said. "Let's get busy."

He selected a sheet of plywood from the pile in the shed, handed Lindsay a hammer and some nails and staggered off in the direction of the appointed tree. Lindsay strutted along behind, grinning the grin of the supremely confident, hammer under one arm, plans neatly tucked under the other.

And so they set to work. Hammers hammered. Nails were driven. Occasional "darns!" and "drats!" emanated from Lindsay. Occasional expletives got deleted from Dad. After seven near misses, four Band-Aids, two splinters and a bumped elbow, all was finished. A few two-by-fours were nailed against the fork of the tree as braces. Stretched on top was the plywood, cut out in places to fit snugly around the tree. Leading to the aerie was an uneven assortment of ladder rungs that had been nailed unmercifully into the tree trunk. ("I did that part," Lindsay said.) And leaning against it, fastened into place, was Lindsay's old wooden slide -- "the fire escape," she said.

It was decidedly hard to spot the foyer, the sunken living room, the French doors, not to mention the fireplace. And there wasn't so much as a smidgen of linoleum. But there was a sign affixed to a prominent branch that warned in runny, painted letters:

"Boys Keep Out!!!!"

Lindsay stepped back to survey her work while Dad held his breath and waited.

"Oh Daddy," she breathed. "It's perfect! Just perfect!"