With only eight Charge to play with—plus the thirty-six in the Ford Explorer already—I couldn’t get too over-the-top with my design. If I were past the bottleneck, it wouldn’t be an issue. There were levels aplenty to be had if we could survive the United Center dungeon. But Tori and I weren’t there yet. We were close. Maybe very close. But not yet.

  So, after a few minutes of tinkering, I decided on two things.

  First, I was going to design the upscaled Heart for the Explorer. But I wasn’t going to build it—at least not all the way. Doing that would compromise the SUV, and I couldn’t guarantee it’d work. We didn’t have time for that; Tori needed gear to overcome the bottleneck, and so did I—and worse, every day we spent on gearing was one less that we spent on securing possible beacon locations. Time was running out before the beacons arrived. So, I wouldn’t build it until I knew it’d work.

  And second, I was going to do it without breaking the Grovetender’s Heart any further. I wanted that Heart intact, because I wasn’t done with it. Not yet. I’d either continue my digging into Charge resonance later, or I’d repurpose the device for…the Voltsmith’s Grasp? Maybe? It’d be an interesting change-up from the rail gun—or a better power source for it.

  Before I knew it, I was halfway through a virtual redesign for the gauntlet, staring at the mostly-scrapped Charge-light Grovetender’s Heart and wondering what I’d been thinking.

  I needed to focus on the most important goal—upscaling the Heart.

  With a wave of the hand, I scrapped the dead-end design and cleared the table. The Heart, now with its top casing back in place to preserve its integrity, sat at its center. I stared at the gears, then walked to the metal bins Cindy had left in the supply room and found bigger versions of about half of them.

  That was a problem. My plan was to replicate the device with the parts I had, and I couldn’t do that if I didn’t have the parts. I either needed to start raiding other parts shops for gears and things—a tough move in a half-grafted world where most of the buildings had been sealed shut—or I needed to start modifying the upscaled Heart.

  The Principle of Scale said that things got weirder the bigger a creation got. Maybe that was true for the design of that creation, too.

  I tried to think back to science class in high school—to biology. The way bodies worked had never interested me. My interests had been in things, not in people. But in the case of the Grovetender’s Heart, the line between mechanical and biological was so thin it was microscopic. What lessons had basic anatomy taught me about hearts? I tried to remember, but I couldn’t. It felt like so long ago, and I hadn’t paid enough attention.

  I was stuck.

  Almost.

  It was late, but there were people in Museumtown who’d be able to help me with this. Jessica might; she was a healer, and maybe she’d learned something about how bodies worked. But my money was on Carol and Zane, for one reason: the twins were old enough to have finished most or all of high school, but young enough to still have fresh memories of it.

  And if they couldn’t help me, I’d ask around. There were a lot of people in Museumtown, after all. There had to be one veterinarian or nurse.

  The next morning, I stood by the fish-hugger fountain, waiting for Carol and Zane to show up.

  Tori and the twins had always met up here when the three of them were trying to break through to Rank One. I hadn’t talked to them—or to her—when I’d arrived in Museumtown the night before, so I could only hope the two of them were creatures of habit. Last night had been a tough night for sleep. Instead of resting, I’d stayed up, trying to feel that pulsing resonance again. It hadn’t happened, and eventually, I realized I wouldn’t be sleeping.

  So instead, I’d spent my night sketching a few different designs for a larger version of the heart. I had those sketches tucked away as I waited for the twins.

  Instead, I got Calvin.

  The old veteran strode toward me, a weary look across his face. “You look exhausted,” I said.

  “Right back at you, Hal. You skipping out on sleep?” Calvin said.

  “I am. There’s so much to do, and so much to understand. I got a new item, and I think I’m close to reverse-engineering it and scaling it up into something genuinely useful—or maybe game-changing—but ‘close’ isn’t the same as ‘got it.’”

  The tale has been stolen; if detected on Amazon, report the violation.

  “It sure ain’t. Tell me what you’re thinking.”

  I laid out my plans on the fountain’s stone border and started pointing. “In the original Grovetender’s Heart, the whole device used four chambers to move Charge through it, a bunch of gears and gizmos to empower it and change it, and this tube here to turn it into a magical effect. It reminded me of real hearts—I saw a lot of them on the farm, but only took one apart once for science class. I was hoping to get some ideas on what the chambers are actually doing from some—“

  “Younger folks,” Calvin finished. I nodded, and he kept going. “Yeah, you’re gonna need someone with a better understanding of how living stuff’s put together than me. I did medic stuff, but my anatomy training’s fifty years old—and I only worked with the practical, not the science stuff.”

  “Right. You were a medic. Maybe you can help me with a different problem. My upscaled heart’s going to have larger…well, everything. Will that cause pressure issues? It would in an engine, but I’m not sure in a vein or artery.” I pointed at the curves in the first sketch’s chamber walls. “I’m thinking I can brace them here and that’ll solve the worst of it.”

  “I don’t see why it wouldn’t cause pressure issues, but you’re probably looking at needing more pressure to keep things moving, not less. A big wound means low pressure after the initial blood loss. Small wound? That’ll spurt for a while before it slows down. So, if you want to maintain the pressure, you either need to pump more stuff or pump it through a smaller gap.”

  “Hey, whatcha got there?” Tori yawned. She also looked tired, and Carol was with her, looking equally exhausted. Zane was nowhere to be seen, though.

  I sighed and started my explanation of the device over, but halfway through, Carol shook her head. “You’re looking at it wrong, sort of. The human heart—or most mammal hearts, really—does two things. First, it moves blood. That’s what you’re trying to do with it, right?”

  “Right. But not blood.”

  Carol pointed. “The other thing hearts do is oxygenate that blood. That’s what half of the thing does. But if you don’t care about that—“

  “Then I don’t need to waste the time and space on extra chambers. I can cut the number in half, which I have the parts for, and focus on moving energy through it without bothering with all the refining and amplification. That’ll work, at least for this prototype. Thanks, Carol,” I said. I rolled up my rough blueprints and stood up. “Tori, no promises, but I might be able to use this to help you out with your gearing. You too, Carol.”

  “Great,” the older girl said. She leaned on her spear. “I’m looking forward to it.”

  Tori didn’t say anything, but the spark in her eyes was more than enough to let me know what she thought of that.

  “I’ll be at Cindy’s all day. The Heart’s there, and so are all my parts. I could use your help, Tori,” I said.

  I didn’t expect her to say yes. And I wasn’t disappointed; she looked at Carol instead, then said, “Sorry, Hal, we’re going to tour some of the nearby Tier Twos. If we get anything you might be interested in, we’ll let you know.”

  “Thanks,” I said, and headed back out of Museumtown’s gates.

  Fewer chambers—and bigger ones with smaller exits. That was the solution.

  I rolled the Explorer all the way into Cindy’s Garage, then carefully pulled the Charge engine I’d built with the shop’s sling-crane. I had plenty of common items to consume for Charge, but I didn’t want to lose what I’d invested in the engine if I didn’t have to.

  Then I started assembling the newer, scaled-up Heart. It’d have to be put together outside of the truck’s hood, then installed all in one go—and that’d mean fiddling around inside of it. But it’d also mean building it to fit, so I started with measurements, then sketched out the space I had to work on the shop floor.

  Every spare gear I could find, and a bunch I’d pulled from the overgrown cars outside, covered the floor around the chalk square. Before I even started, though, I had to lay out the device’s walls. I did that with a pair of fuel tanks I’d taken from Cindy’s Garage’s supply room, after I’d cut them in half and opened them up. They’d be the beginning of my chambers once I took them apart and turned them into two moving, pumping parts.

  That’d take a lot of gears, working in quarter-turns, or even smaller amounts, to transfer the energy from whatever drove the Heart to the…bellows. Yeah, the steel-clad bellows I was designing. I started by laying out the gears without cutting into the first tank’s steel, only adding the cogs and gears to their spots once I was sure I had enough of the right sizes.

  Then I hand-spun the first one, sending the whole device into convulsions. I grimaced and added two more: an absolutely tiny gear on one end, and a gigantic, rusted one on the other. The tiny one spun as fast as it could, but between its small size and the friction I’d increased with the big one, it hardly moved the others. They lifted slowly, then pushed down just as slowly.

  It was perfect. The first part of the upscaled Heart was finished. Only three more identical parts, then a contained Charge system to keep it running, and I’d be—

  Something thumped in the shop.

  A woman’s voice cursed.

  And my whole body tensed. It didn’t sound like Jessica Silvers—she rarely cursed—and Tori and Carol were both dungeon-clearing. It could have been anyone from Museumtown, but only a few people knew where my Voltsmith’s Laboratory was. And someone like Theresa Mays, from the Rat’s Nest, wouldn’t come this far—and couldn’t move that quickly, not through monster-infested streets. There were too many orcs and other Solemnus-Six creatures out there.

  That meant a stranger. My hand flexed the Voltsmith’s Grasp and reached for the Trip-Hammer. I didn’t have my armor, since all of my bomb-making drones were still at work on the far side of the lab.

  “Hello,” I said loudly. “Who’s there?”

  The woman stepped through the door between the office and the work floor, holding the hilt of a curved sword in one hand. It was sheathed, but her eyes were locked on my hammer. Her other hand held a thin, pointed dagger with no blade; I recognized it as similar to the armor-piercing dagger I’d welded onto the Trip-Hammer.

  “You have something of mine,” she said. Her eyes flicked to the Explorer as she talked. “I’m here to pick it up.”