“Isn’t all science theoretical?”

I shrug. She’s made a good point, but it’s not like I’m going to admit that. “Plus, I shouldn’t be talking to you.”

“Because of what Parker did? Because he’s the reason Mabel’s dead?”

There’s another whistle in the distance. I’m thankful for it because it helps distract me from the momentary shock of what Quinn just said. I can’t believe she came out and, well, said it. Even Grams uses euphemisms when it comes to how Mabel died, saying things like It was her time to pass or Now she’s resting in peace. When I told her that once, she told me that euphemism is a million-dollar word. I know Grams thinks it’s snotty that I collect “million-dollar words,” but I don’t collect them to show off. I just like knowing things. The more things you know, the less likely you are to be taken by surprise.

I glance around. I wonder how many people have logged Quinn and me talking. They probably have decided I’m a rotten and traitorous sister. I don’t blame them.

“Yes. Because of that,” I say.

“But—” Quinn pauses. For a second, I worry that her brain is having one of its freeze-ups, but she gives me three blinks to signal that no, she’s not freezing up, and yes, she is fine, and she just needs a moment to collect her thoughts.

“But?” I prompt.

“But we if we work together to change what happened, it’s not really like you’re . . .” Quinn shakes her head and tries again. “It’s not like you’re really hanging out with me or that you’ve forgiven me. It’s because you want to help Mabel. Sorry. I don’t know if that makes sense.” She bites the inside of her cheek. “I don’t have the right words.”

I frown. “Are you trying to say that it would be okay for us to hang out if we’re working on this because it’s not like I’m actually being your friend again, more that we’re working together to . . .” It’s my turn to grasp for words.

“Save Mabel,” I finally settle on. The words tumble out of my mouth and land at my feet with the weight and pull of gravity. Dad is always reminding me that gravity is the most powerful force on the planet.

Quinn’s tiny smile transforms into a lopsided grin. “I knew you would get it.”

I tilt my head back. The sky is a shade of blue that I always see described in books as drinkable, but water actually isn’t blue. It’s clear. It’s the sunlight that gives it color. And the sky only appears blue because of the length of the light rays coming from the sun. I used to tell Quinn facts like that all the time, but I’m going to keep this one to myself. I keep waiting for her to say something, to fill in the silence. She doesn’t, of course. When I look at her, I find her patiently watching me.