How do we get close enough to see it?”

Tom stared up at the golden Pegasus, the winged horse, that had been painted in the corner of the Grand Central ceiling.

“ ‘Through Mercury’s gate, you’ll reach the backward horse,’ ” his dad repeated for maybe the hundredth time in the last twenty minutes.

“We all got that part, Big T,” said Noodle with an exaggerated eye roll.

“ ‘The circled rose will light your course.’ ” Mr. Edison whispered the second part of the riddle softer to himself. His hands hadn’t stopped shaking from nerves and excitement.

“What circled rose?” Tom scanned the entire ceiling for some kind of clue, a sign, anything. “I don’t see it anywhere.”

“The only way to find out what it means is by taking a much closer look at that horse.” Mr. Edison took several steps one way, then another, in hope of seeing the problem from a different angle. It wasn’t working.

All around them, commuters were flooding the station’s Main Concourse as the evening rush hour ritual began. Uniformed police officers had begun popping up all over the place, too, and Tom couldn’t help noticing the sheathed guns and nightsticks holstered at their waists.

“Shame I left my web spinners at home,” said Tom, letting out a frustrated sigh.

“Like I’ve always said, nothing’s ever easy with the old Sub Rosa.” Colby collapsed onto a nearby bench and dropped her head in her hands. It was the second time she’d closed her eyes in almost forty-eight hours, and she could feel herself quickly dozing off.

“Spider-Man, huh.” Tom’s dad wiped his glasses with the bottom of his still-damp shirt. “It’s an interesting proposition.”

“Where’re you going with this, Dad?”

“Well, I know it might sound crazy, but …” His voice trailed off.

“But what?”

“No, never mind. I really shouldn’t even be thinking like this.”

“Out with it, Big T.”

“Well.” He paused for a moment. “Remember the Clorox SuperDuperStick patent you helped me with last summer?”

“Yeah, but we couldn’t get it to work.”

Mr. Edison nodded. “Because I think we didn’t use a strong enough binder. Perhaps if we reworked the ratios a little …”

Tom felt a small flicker of anticipation zap his stomach. “We’d need to find Zytrol somewhere, though. And oil, resin. Some sort of compound to make rubber.”

“And a hot stove.” Lost in thought, Mr. Edison rubbed his forehead and paced away from the group about ten yards.

“Plus, it’d be dangerous,” said Tom, catching up to walk alongside him. “I’m not sure I could get high up enough before the solution—”

“Oh, no. You wouldn’t be the one going up,” said Tom’s dad. “I would.”

“You sure that’s a good idea? You’re old.”

“I’m not that old, wise guy.” He gave Tom a light smack on the back of the head. Tom grinned. It was nice to see his father so intrigued. It had been a long time since Tom had witnessed that. “And no. I think this is all one big terrible idea, but I’m all out of any better ones—”

“And I have no clue what the two of you are talking about when you speak in Edisonian geek ciphers,” Noodle interrupted, trailing them.

“Trust me, it’s better that you don’t,” Tom called back as he scanned the concourse for some place where they might find the necessary ingredients for SuperDuperStick. “What about that restaurant?” he said, pointing toward the Oyster Bar at the end of a lower walkway, just off the Main Concourse. “They’ve gotta have stoves at a fancy place like that, right? And maybe the ingredients we need.”

“It’s worth a shot,” said his dad.