It’s a little cooler in the tree house. The leaves over our heads give us plenty of shade. A breeze dries our sweaty faces. We drink the rest of our open bottles of water and take out our books from the summer reading list. Some of them are long and hard, some short and easy. Skylar tends to pick the shorter ones. She’s reading The Hunger Games now, which she’s already read twice. It’s not cheating, she says, because every time she reads it, she notices something she missed the other times.

I’m reading Never Let Me Go. So far it’s pretty good. These kids live in an upscale orphanage or boarding school. I’m not sure which. When I checked it out, the librarian told me not to tell anyone about the big surprise. So far, I haven’t come to that part, but when I do I’ll keep it secret. I hate it when people give the plot away and ruin the whole book.

Suddenly Skylar nudges me. “Get down. A car’s coming.”

We stretch out on our stomachs and look down at the road. A black SUV slows to a stop and parks right under our tree. A couple of minutes later, a little gray car pulls in behind it, the kind you see everywhere. No matter what make they are, they all look the same to me.

A woman gets out of the car. I can’t see her face, because she’s wearing huge sunglasses and a granny-style wide-brimmed straw hat. She gets into the SUV. Its tinted windows hide the driver, but I know it’s a man when he says, “Hey, you—going my way?”

She laughs and shuts the passenger door. The SUV makes a U-turn and heads back up Marie Drive.

“What’s that all about?” I ask Skylar.

She studies the gray car. “Maybe the woman is married and she’s meeting the man in secret. Or maybe he’s the one who’s married. Or they both could be married—to other people.”

“That’s boring,” I say. “It would be more interesting if they’re criminals or spies.”

“Like that TV show about the Russian spies who pretended to be ordinary Americans,” she says. “I loved their disguises. It’s amazing how different a wig can make you look.”

“Russians really do spy. They even poison people,” I say. “They hack into computers and all sorts of stuff.”

Skylar stretches out on her back, hands behind her head. “Remember back in the days of Nancy Drew, when we played detective?”

I laugh. “We really thought we’d catch a crook and become famous girl detectives. Like Nancy, of course.”

“But the people we followed always turned out to be ordinary boring adults.” Skylar rolls over and stares down at the gray car. “Those people are definitely not ordinary. They’re up to something.”