I looked down at the practice sheet he’d given me, problems lined up across it. As usual, with just one glance I felt my heart sink, my brain going fuzzy around the edges. If this was my instinct talking, I didn’t want to hear what it was saying.

“Zen mode,” Gervais said. “Clear your head, accept the uncertainty, and the solutions appear. Just trust me.”

I was not convinced, and even less so when he presented me with his instructions for my last weekend of studying. (Which, incidentally, were bullet-pointed and divided into headings and subheadings. The kid was nothing if not professional. ) Saturday morning, I was supposed to do a final overview, followed in the afternoon by a short series of problems he’d selected that covered the formulas I had most trouble with. Sunday, the last full day before the test, I wasn’t supposed to study at all. Which seemed, frankly, insane. Then again, if the goal was to forget everything by Monday morning, this did seem like the way to do it.

Early the next morning, I sat down on my bed and started my overview, trying to focus. More and more, though, I found myself distracted, thinking about Nate, as I had been pretty much nonstop—occasional calculus obsessions aside—since I’d seen him swimming a couple of nights earlier. In the end, both Harriet and Cora had heard from Mr. Cross, who was wildly apologetic, crediting Harriet’s account and offering Cora a free week’s worth of walks to compensate. But in the days since, whenever I’d seen Nate across the green or in the halls at school, I couldn’t help but notice a change in him. Like even with the distance between us, something about him—in his face or the way he carried himself—was suddenly familiar in a way I hadn’t felt before, although how, exactly, I couldn’t say.

After two hours of studying, I felt so overwhelmed that I decided to take a break and quickly run over to get my paycheck from Harriet. As soon as I stepped off the greenway, I saw people everywhere—lined up on the curb that ran alongside the mall, gathered in the parking lot, crowded at the base of a stage set up by the movie theater.

“Welcome to the Vista Five-K!” a voice boomed from the stage as I worked my way toward the main entrance, stepping around kids and dogs and more runners stretching and chatting and jogging in place. “If you’re participating in the race, please make your way to the start line. Ten minutes to start!”

The crowd shifted as people headed toward the banner— VISTA 5K: RUN FOR YOUR LIFE!—strung between the parking lot and the mall entrance. Following them, I kept an eye out for Olivia but didn’t see her—just runners of all shapes and sizes, some in high-tech lycra bodysuits, others in gym shorts and ratty T-shirts.

Inside the mall, it was much quieter, with few shoppers moving between stores. I could still hear the announcer’s voice from outside, along with the booming bass of the music they were playing, even as I walked from the entrance down to the kiosk courtyard, where I found Harriet and Reggie standing at Vitamin Me.

“I’m not doing the fish oil,” she was saying as I walked up. “I’m firm on that.”

“Omega-threes are crucial!” Reggie told her. “It’s like a wonder drug.”

“I didn’t agree to wonder drugs. I agreed to take a few things, on a trial basis. Nobody said anything about fish.”

“Fine.” Reggie picked up a bottle, shaking some capsules into a plastic bag. “But you’re taking the zinc and the B-TWELVE. Those are deal breakers.”

Harriet shook her head, taking another sip of coffee. Then she saw me. “I thought you might turn up,” she said. “Forget vitamins. Money is crucial.”

Reggie sighed. “That kind of attitude,” he said, “is precisely why you need more omega-threes.”

Harriet ignored this as she walked over to her register, popping it open and taking out my check. “Here,” she said, handing it over to me. “Oh, and there’s a little something extra in there for you, as well.”

Sure enough, the amount was about three hundred bucks more than I was expecting. “Harriet,” I said. “What is this?”

“Profit-sharing,” she said, then added, “And a thank-you for all the work you’ve put in over the last months.”

“You didn’t have to do this,” I said.

“I know. But I got to thinking the other day, after we had that talk. You were right. The KeyChains, all that. I couldn’t have done it without you. Literally.”

“That’s not why I said that,” I told her.

“I know. But it made me think. About a lot of things.”

She looked over at Reggie, who was still adding things to her bag. Now that I thought of it, she had been awfully receptive to that zinc. And what was that about a few things, on a trial basis? “Wait,” I said, wagging my finger between his kiosk and ours. “What’s going on here?”

“Absolutely nothing,” she replied, shutting the register.

I raised my eyebrows.

“Fine. If you must know, we just had drinks last night after work, and he convinced me to try a few samples.”

“Really.”

“Okay, maybe there was a dinner invitation, too,” she added.

“Harriet!” I said. “You changed your mind.”

She sighed. Over at Vitamin Me, Reggie was folding the top of her bag over neatly, working the crease with his fingers. “I didn’t mean to,” she said. “Initially, I just went to tell him the same thing I said to you. That I was worried about it not working out, and what that would do to our friendship. ”