"There's a person here, Roof. You need to come home."

"Here where? In the house? You let a stranger in the house?"

"Well she's just a girl. Or like a young woman or whatever."

My phone was fading again. It does that. Mom got it as a cheap add-on to her own cell.

Or: Maybe the stranger had her hands around Josie's throat?

Every single lesson we'd been taught about what to do when we were home alone--and our mom and dad take their child-rearing way more seriously than any normal parents--was racing through my head. 911 flashed in big red numbers. "Josie!" I shouted. "Can you hear me? Should I call the police?"

"No! You idiot!" No problem with the volume now. I held the phone a few inches from my ear. Then Josie's voice dropped to a whisper. "This isn't dangerous, Roof, only kind of... weird. Just come home, 'kay?"

Rufus Peters has never felt exceptional in any way. How could he, with a twin sister who outshines him at everything they do? His two problems are finding a way to wiggle out of a student exchange to Quebec, and liberating Boreas, his skateboard, from the principal's contraband cupboard.  After Amelia knocks on their door, life in the Peters family goes from plain old "Just Cheese Please" to Nick's Pizza's "Grand Slam and More." Roof makes it his mission to solve The Mystery of the Mexican Stranger.