Mara clicked the file. Keyplan 3D opened with its familiar chime—too cheerful for 11 p.m. on a Tuesday. The second floor materialized on screen: a perfect wireframe ghost of what should have been. She spun the model, layer by layer. Subfloor. Joists. Wall framing. Roof trusses. Everything green-lit in the software’s structural analysis. No warnings. No errors.

Mara closed Keyplan 3D. The second floor vanished from her screen, but for the first time in six months, she felt solid ground beneath her feet.

At 3 a.m., she had it. A new model. Ugly. Compromised. True.

The west wall now tapered. The nook lost six inches of headroom. The storm closet moved to the stairwell landing. It wasn’t what the Whitmores had wept over. But it would stand.

She zoomed into the southeast corner—the nook. In real life, that corner sat over a void: a chimney breast that had been removed in the 1970s but never documented. Keyplan didn’t know that. How could it? Garbage in, garbage out. Except the garbage wasn’t hers. It was the original architect’s, from 1923, whose hand-drawn plans had been digitized and sold as a “verified historical model” on an asset marketplace.

She opened the asset properties. There it was: Source: AI-generated reconstruction, 2021. No survey. No site visit. Just an algorithm hallucinating joist spans from a fuzzy scan of yellowed vellum. She’d built a castle on digital quicksand.

The blueprint was a lie, but the software never blinked.