Page 96 of The Eagle's Vault

“What’d Brie come up with?” she asked, pointedly changing the topic.

“While Declan was busy playing hero,” Brie said, “I created a model of how water would flow across the vault door’s surface. The door isn’t as vertical as it looks. There’s a gentle grade to it, with textures you can barely see. Think of it like a game of Plinko. The water would divert around high spots and flow across low spots.”

I held up Declan’s phone to display the model as augmented reality.

Brie’s overlay splashed the live view of the vault door in hues of green, tracing the paths water would take from the terracotta pipes above, down the curves and glyphs on the stone. The digital waterfall avoided five of the twelve symbols.

Jayce’s brow furrowed. “So, water doesn’t cover five of the symbols—”

“Which means there’s either a keyhole,” I said, “or something we need to manipulate in at least one of them.”

A ragged groan slipped from Daniel, looking as if he’d just survived a marathon. “Not very good at playing lookout, but I make a mean pylon.”

I angled the phone so he could see it. “We’ve got our next clue.”

“Declan will be fine. Nothing’s actually broken, but I’ve covered up the wound.” Rav strode over to us, lethal precision in his every move. His gaze flicked pointedly to Isaac. “Scarlett says the police are checking the entrance, so I’m going to collect the other man first and deliver him. If sleeping beauty so much as twitches, try to be useful.”

Isaac’s jaw clenched, but he kept his mouth shut.

Rav inclined his head toward Declan. “He’s got the gun, so all you need to do is alert him.”

Daniel said, “I know another way out if you want to avoid the police.”

“Good plan,” said Rav. “You have exactly as long as it takes me to deliver these two to the police. Depending on how fast they can convince the authorities to search for trespassers, you may not have much more than an hour.”

Declan handed Rav a headlamp, and the big man was off at a jog.

Daniel limped toward the work lights, adjusting one of them to illuminate the pipes better. “I didn’t put all of my research into the notebook. I suspected da Vinci’s sketches of Platonic solids could be crucial.”

Jayce stifled a laugh. “What, like solids who are just friends?”

Daniel blinked, and I couldn’t hold my own laugh in.

“Three-dimensional shapes,” I said. “There are five core ones through history, like a cube or a tetrahedron. No one’s sure who first came up with the concept, but Plato hypothesized they made up the Earth and universe.”

“I need a snack after that.” Jayce dropped her pack to the floor and began rummaging. “Declan, where’s that chocolate you promised?”

Declan waved her to the spot where Rav had stationed him. “In my bag.”

I turned back to Daniel. “Do you think the solids play a role in this? It might explain why they’re on the frescoes.”

Daniel nodded, standing taller the longer he spoke, as though he gained strength from the intellectual discussion. “Da Vinci put substantial weight on symmetry and balance, even in the Platonic solids. The dodecahedron is special. It has twelve faces, corresponding to the twelve zodiac signs”—he gestured to the carvings on the door—“and is often associated with the aether or spirit, while the other four are linked to the elements.”

I hummed in assent. “Fire, water, earth, and air.”

“Exactly. And the surface area and volume of a dodecahedron are related to the golden ratio, which da Vinci also studied extensively.”

I nodded. It was a detail I knew. “He used it in many of his paintings and sketches.”

Jayce rolled her eyes, unwrapping a bar of dark chocolate Declan had handed her. “History lessons later, people. Rav’s only going to take so long.”

“Sorry, I didn’t…” I winced, the apology slipping out before I could stop it.

Jayce waved a hand dismissively. “Save it. Every sorry is another second wasted.”

Declan groaned, pushing himself up. “If one of those five carvings that aren’t under water is the keyhole, maybe there’s a way to overlay the golden rectangle?”

“Or the golden spiral?” I ventured, the idea taking hold.

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