“That one,” Leo breathed, tapping the screen. “Right there.”

That’s when Leo saw it. On Ben’s tablet, which was propped against the IV pole, a strange application was open. It wasn’t the usual clinical scheduling software. It looked like a topographical map. A faint, pulsing blue glow traced the inside of an arm— his arm.

“Try this,” he said. And for the first time, the map wasn’t just for him. It was for everyone lost in the wilderness of their own skin.

He didn’t use it to replace the nurses. He used it to help them. The next week, when a panicked intern couldn’t find a line on a crying child in the bed next to him, Leo held up his phone.

“It’s a download,” he said, more to himself than to Ben.

The problem wasn’t the needle. The problem was the map.

“Neither has anyone else. That’s the point.”

With trembling hands, Ben sanitized the spot. He aligned the tablet’s augmented reality view with Leo’s actual arm. A ghost-blue crosshair appeared on Leo’s skin, hovering exactly over the hidden river. Ben picked up the catheter. He didn’t palpate. He didn’t tap. He just trusted the map.

Every time he started a new round of IV antibiotics, his body felt like a foreign country. He never knew which vein would be the highway and which would be the dead-end dirt road. Last month, the nurse had blown three veins on his left hand before giving up. Leo had left looking like a pincushion, his knuckles bruised purple and yellow.

Ben grinned, finally relaxing. “Want me to send you the APK? It’s not on the public store. You have to get it from the closed clinical trial forum.”

“You have ‘adventurous’ vessels,” the nurses would say with a pitying smile. Leo hated that word. Adventurous. His veins weren’t on a hike; they were hiding.

The needle slid in. Smooth as a key turning a lock. A perfect flash of blood in the chamber. Ben flushed the line. No resistance. No burning. No blowout.

“It looks like a vein map. Of my arm.”

“What is that?” Leo whispered.

Ben’s eyes went wide. “I’ve never tried that spot.”